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Contraceptive choice and cervical cytology
Contraceptive JERRY C.
J.
choice and cervical cytology
SHULMAN,
GARY
MERRITT,
Philadelphia,
Pennsylvania
M.D.,
M.P.H.
PH.D.
The prevalence rates of atypical cervical cytology among two groups of contraceptive choosers were determined. Choosers of the intrauterine contraceptive device (IUD) and the oral contraceptive pill with no reported history of contraceptive use and choosers of the IUD and pill with a prior history of use of methods of contraception other than the pill were found to have small differences in screening rates of cervical cytologic atypicality. When the cervical cytology atypicality rate is described by both current and past reported methods of birth control, it is evident that contraceptive history is associated with differential rates of cervical cytology atypicality among choosers and that any comparison between choosers should control for past use of all major methods of birth control. The similarity in atypical cervical cytology rates may reflect a similar sexual history in IUD and pill choosers, but a study which includes more specific cytologic designations and detailed measures of contraceptive history and behavioral variables is necessary to evaluate this hypotheses. A prospective study which includes these variables in evaluating the relative rates of atypical cervical cytology among choosers of various methods of birth control is described.
UNTIL RECENTLY, there has been little evidence indicating whether choosers of specific contraceptives differ in their rates of atypical cervical cytology prior to their contraceptive choice. However, Stern and associates? reported, in 1970, that within a group of Los Angeles family planning patients who had not previously used oral contraceptives those who chose the pill had a
higher prevalence of cytologic dysplasia at the time of choice than women who chose the intrauterine contraceptive device (IUD), though both groups of women were similar in demographic characteristics.’ Earlier, Melamed and colleagues”, B had presented New York family planning clinic data from which it could be shown that among women were just beginning the use of who diaphragms as compared to those beginning oral contraceptives the latter were at greater risk of cervical dysplasia and more advanced forms of abnormal cervical cytology. These findings occasioned some surprise. An editorial note appended to a summary of the article by Stern and co-workers’ raised the question: “. . . what in the world can it be that makes pill selectors have a greater likelihood of dysplasia or carcinoma in situ than do diaphragm users in New York and IUD users in California?” Needless to say, the findings are of considerable interest in evaluating the subsequent incidence of abnormal cervical cytology in women who continue methods over a period of time.
From the Department of Obstetrics and Gynecology, ‘Temple University Health Sciences Center and the Institute for Survey Research and the Department of Sociology, Temple University. The collection of data for this paper was supported in part by OEO Grant CG 8250 to the Population Council and OEO Grant CG 2810 to the American Public Health Association. The collation and analysis were supported by the National Institutes of Health. Contract No. NIH-71-2299. ’ 1 Received for publication October 1972. Revised February 5, 1973. Accepted February 15, 1973. Reprint requests: Dr. C. Gary Institute for Survey Research, University, Seltzer Hall, 1710 St., Philadelphia, Pennsylvania
23,
Merritt, Temple N. Broad 19121.
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Implications and questions raised by these findings elicited the present study. We undertook to determine the cervical cytology characteristics at the time of contraceptive choice among a group of women attending a family planning clinic in Philadelphia, and we explicitly controlled for contraceptive history. We sought to compare atypicality rates among women who reported that they had not used contraceptives for at least two years with rates among women who did report use of specific contraceptives in that period. The findings, some interpretations, and pointers for future research are presented. Methods
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August
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Temple University Health Sciences Center (TUHSC) is located in a predominantly black. low socioeconomic area of North Philadelphia. Women who use this family planning program are either postabortal and postpartum inpatients or outpatients who request family planning services. At the present time, most contraceptive acceptor patients receive their initial medication and/or devices as inpatients or by referral from various community groups. The different contraceptive methods available and their side effects and efficacy are explained to each patient by a specially trained. indigenous Family Planning Counselor, and the patient’s choice is then noted on her prenatal record or on her outpatient chart. A medical history is taken and an examination performed by a resident physician. A Papanicolaou test is done and, providing tilere are no contraindications, the patient is given the rnethod and/or device of her choice. If she is an inpatient, the method of choice is provided in the hospital; if she is an outpatient, the method is provided at the time of her visit. A small, undetermined percentage of the patients are denied their choice by the physician. This information cannot be retrieved from the files rind so the patients described in this report include a few whose method was different from their choice for medical rea-
Am.
J. Obstrt.
15, 1973 Gynecol.
sons and some whose %hoice” rested upon clinic personnel recommendation. Following her acceptance, that patient sees the counselor who fills out the National Center for Health Statistics form for the visit. This interview includes an item on contraceptive history during the “past two years.” An undetermined number of women may have used some method prior to the two years, though we estimate that this was a small number in view of the relatively young ages. The data here are reported as indicating a complete contraceptive history, and the reader should bear in mind this constraint in measurement. Since 1967, a computerized file has been compiled on the cytologic specimens read at TUHSC and on the histologic reports received by the Department of Obstetrics and Gynecology. Cytology classifications were recorded with a simple system of designation : negative, atypical, suspicious, and positive. In 1969, the Family Planning Project was begun. Since then, demographic information on these patients has been recorded on the National Center for Health Statistics Provision Report Form for Family Planning Services. A master file was created and has been kept at our computer center for (family planning) reporting and administrative purposes. All patients seen for the family planning program receive a unique number, and this number is also used to identify any ancillary service, such as the Papanicolaou smear, and any subsequent histologic examination. A program was written to collate the family planning and cytology-pathology tapes, and the data presented in this report were obtained by programming and tabulating variables from the combined tape. Results
In the December, traception Of these. had used last two
period November, 1969, through 1971, 5,343 women seeking conwere examined and interviewed. 2,352 women indicated that they no contraceptive method within the years. Papanicolaou results were
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Contraceptive
Table 1. Demographic contraceptive choosers
characteristics Method
Demographic category Ethnicity White Nonwhite Education <9 29 Income < $25 week 2 $25 week Age < 18 18-23 > 23 Parity 0 >: _.
Total
1
(No.
Pill = 1,204)
%
1 Ay$$al
and
rates
of
of contraception (No. r.
IUD =
atypical
and
cytology
cervical
among
cytology
1081
new
chosen
304) / A?.$71
(No. %
Other =
431)
(No.
Total = 1,939)
/ Atj$;al
%
1 Ay$i;al
6.7 93.3
13.6 19.1
7.2 92.8
4.6 21.3
3.9 96.1
23.5 17.2
6.2 93.8
13.3 19.0
35.6 64.4
17.7 19.4
39.8 60.2
22.3 18.6
41.8 58.3
16.1 18.3
37.7 62.4
18.1 18.9
74.0 26.0
18.5 19.5
80.3 19.7
19.7 21.6
76.6 23.4
16.7 19.8
75.6 24.5
18.3 19.5
33.4 49.4 17.2
15.4 20.8 18.8
33.9 43.8 22.4
15.5 21.0 25.0
16.2 41.1 42.7
17.1 17.5 17.4
29.7 46.7 23.7
15.7 20.2 19.”
17.8 52.3 29.9 100.0
16.4 16.8 23.3 18.7
7.2 53.6 39.1 100.0
9.1 19.0 23.5 20.1
6.5 35.3 58.2 100.0
14.3 13.8 19.9 17.4,
13.6 48.7 37.7 100.0
15.5 16.7 22.2 18.6
retrieved on 2,304 of these patients, of whom 1,939 elected to use pills, an IUD, or “other methods” of contraception (diaphragm, foam, tubal ligations), while 365 elected no method. Table I pertains to the 1,939 new acceptors who reported no recent use of any method of birth control. It presents a description of basic population demographic characteristics and the screening rates of Papanicolaou smears by demographic categories. Our cytology laboratory used the cytologic descriptions “negative, ” “atypical” (apparently benign ) , “suspicious,” and “positive.” The “suspicious” category includes those classified by the Papanicolaou system as III, plus a category called “mild to moderate dysplasia.” “Positive” includes those classified as Papanicolaou Class IV and V. In this series, the atypical cytologic grouping includes all smears Pap II and above. The bottom row of Table I (Total) shows the over-all screening rates of atypicality by categories of method selected. Also shown are the distributions of patients in each selector group by
-
demographic categories and, within each demographic status, the rate of atypical cytology. The new acceptors are 94 per cent nonwhite; 38 per cent have less than a ninthgrade education; 76 per cent fall in the lower income group; 30 per cent are 18 years old or less; and 14 per cent are nulliparous. Demographic distributions by method selected show certain small differences between the groups. We wish to focus on the oral contraceptive and the IUD groups where, for example, oral contraceptive users are slightly more likely to be black (93.3 versus 92.8 per cent), somewhat better educated (35.6 and 39.8 per cent, respectively, have no high school education), of higher income (26.0 versus 19.7 per cent), younger (17.2 versus 22.4 per cent are over 23), and decidedly more likely to be nulliparous (17.8 versus 7.2 per cent). Parity is the only variable which reveals sizable differences between the two groups; in other respects they are quite similar. Atypicality within these groups fails to
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Table II. Demographic characteristics and rates of atypical cytology contraceptive choosers who have not previously used oral contraceptives Method Pill (No. = 1,434) Atypical
Demographic categorier
of contraception
Other (No. = 712) Atypical
(%)
70
(%)
70
13.3 19.5
7.2 92.8
L2.7 17.8
4.1 95.9
33.3 66.7
18.4
24.9 75.1
18.9 16.9
37.7 62.3
73.0 27.0
18.3
78.5 21.5
17.7 16.5
29.6 49.5 20.9
15.3 20.9
14.9
13.9 21.4 16.0
16.7 47.9
15.4 17.3
35.4
23.3
Ethnicity 6.8 93.2
Education <9 29 Income < $25 week 2 $25 week -he <
18 18-23
> 23 Parity 0 Total
__-
chosen
IUD (No. = 873) Atypical
70
White Nonwhite
among
100.0
19.5
21.1
20.4
19.1
32.1 53.0 4.9
28.5 66.6 100.0
show any notable pattern of differences. Over all, IUD choosers appear to be at a slightly greater risk: 20.1 versus 18.7 per cent. This difference ( 1.4 per cent) can be largely accounted for in terms of the different distributions of the groups in the categories of parity. Interestingly, at higher parity the groups are at almost identical risk (23.3 versus 23.5 per cent). The larger differences (for example, white rates of 13.6 and 4.6 per cent, respectively) are regarded as unreliable due to small numbers, e.g., one case among 22 choosers of the IUD. These findings are based on new acceptors. What occurs when the population is enlarged to include women who report previous use of nonsteroidal contraception? In the ios Angeles study the criteria for inclusion were i‘ . that the women are new to the family planning program and that they have not used the contraceptive pill.“S Similarly, the New York data probably included as pill selectors xvomen who were changing to it from other methods. Table II shows the results of this amplification of the selector population to 3,019 patients. Note that the gradient of risks now shifts toward pill selectors: 19.1 versus 17.4 per
11.6 16.5 18.2 17.4
Total (No. = 3,019) Atypical %
(%I
9::;
14.2 18.9
19.1
31.9 68.1
18.7 18.6
77.4 22.6
19.1 19.0
75.6 24.4
18.3
11.5 35.7
22.0 16.9
21.1 41.2
20.2
52.8
20.0
37.7
18.5
5.9
14.3 15.8
10.8 37.3
14.8 16.9 20.7
26.7 67.4 100.0
(%!
20.7 19.0 19.0
20.8 19.1
51.9 100.0
19.5 15.9
18.6 -
cent of the IUD selectors (Total). Again, however, the differences are small. The overall rates of atypicality for the populations of Tables I and II are identical: 18.6 per cent. This means that previous users of nonsteroidal methods have the same rates as previously noncontracepting women but that previous non-oral contraceptors who change to the pill are at greater risk than those who retain or change to IUD’s, In pooling the two populations, the IUD group appears to have received proportionately more of the better educated (60.2 per cent in Table I to 75.1 per cent in Table II) ( the older (22.4 to 53.0 per cent), and the multiparous (39.1 to 66.6 per cent). Distributions of ethnicity and income were largely unchanged. The sizable increase in the proportion of IUD users with two or more children was accompanied by a lessening of the rate of atypical classifications in this category, while pill proportions remained constant. The breakdown of rates by primary method used during the previous two years is shown in Table III. Here, column totals show that among women newly choosing or reaffirming previous contraceptive choices
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Table III. Rates of atypical cervical cytology; past and current methods of contraception Present
contraceptive
Pill
Past contraceptive Pill IUD
Other contraceptive No contraceptive Total
Total (No.)
AtyPical ( (No.)
1,085 108 1’2 1,204
216 22 27 “25
2,519
490
prevalence
among
Total (No.)
19.9 207 20.4 524 45 22.1 304 18.7 19.5--~_- 1,080
there are small differences. Pill, IUD, and diaphragm choosers show rates of 19.5, 18.0, and 18.6 per cent, respectively. Notice, however, that the row totals show more sizable differences. Past IUD users (16.2 per cent) and users of other methods (24.0 per cent) represent the extremes, with “no contraceptives” (18.6 per cent) and pill (19.5 per cent) as the intermediates. Within Table III one of the more interesting observations is the relatively high rate of atypical cytology contributed to the pill chooser group by women with a past history of use of IUD’s (20.4 per cent) and other methods (22.1 per cent). Among current pill choosers, women who are continuing with pills (19.9 per cent) and those who report no contraceptive history (18.7 per cent) show lower rates. Patients who are continuing with IUD’s (15.1 per cent) have the lowest rates of any of the twelve subgroups. Table III shows that the effect of the inclusion of 746 previous IUD users and 334 “others” is to add to the pill choosers (in Table II ) proportionately more atypical cytology and so slightly raise the rates in this group. The net result is to shift the higher prevalence of cervical cytology atypicality from IUD choosers to pill choosers by adding those wth a history of using methods other than the pill. In summary, if there was no recent history of contraceptive use, there was little difference in the over-all prevalence of cervical cytologic abnormality in IUD and pill choosers. Impressions gained from Tables I,
Atypical (No.) 42 79 12 61 194
cervical
4,653
cytology
patients
1083
by
choice
IUD AtyPical rate (75)
and
AtvPical rate (76) 20.3 15.1 26.7 20.1 18.0
Other
contraceptive
Total (No.)
ical (No.)
342 114 167 431 1,054
60 20 41 75 196
17.5 17.5 24.6 17.4 18.6
Total
1,634 746 334 1,939 4,653
318 121 80 361 880
19.5 16.2 24,.0 18.6 18.9
II, and III reinforce the notion that contraceptive history is associated with different rates of atypical cervical cytology and that any contrast of rates between choosers should control for past use of all major methods of birth control. It should be recalled that the patients in this population were seen over a 26 month period of time. A perpetually vexing problem in drawing inferences from aggregate cytology data concerns shifting standards of over time, the cytologic interpretation pronounced differences between readers, and the extent to which populations can undergo rapid changes in the prevalence of infectious agents which may be reflected as an increase in rates of atypical readings of the Papanicolaou smears. With these problems in mind we sought to examine their expression in these data. In order to determine whether or not rates of ( 1) atypical cytology and (2) proportion of patients prescribed pills were constant over the 26 months, these data were examined chronologically. Fig. 1 shows a severalfold increase in the proportion of atypical reports within each of the chooser groups. The proportion of patients choosing steroidal methods remained relatively more constant, with an early decline which subsequently stabilized around 45 per cent. Comment
If we may assume standard cytopathologic descriptions, at least four specific questions should be raised in evaluating discovered differences in rates of abnormal cervical cytology among groups of contraceptive
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August 15, 1973 Am. J. Obstet. Gynecol.
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3-5
4-6
5-7
6-6
7.9
WI
llllllll I,,,,,, 911 IO-12 II-13 12-14 1315 1416 15.17 16.16 17-19 18-20 19-2, a?-22 21.23 22.~~25
l-26
MONTHS -
% STEROID
-
16 OF STEROID
CHOOSERS
-
% OF IUD CHOOSERS
CHOOSERS WITH
WITH
ATYPICAL
ATYPICAL
CYTOLOGY
CYTOLOGY
Fig. 1. The percentages of the total population choosing oral steroids and the percentages of steroid and IUD choosers with atypical cytology: 26 month time trend. choosers : (,1) Do the contraceptive groups differ in their prior experience with cervical cytologic examinations? (2) What is the relative disparity between contraceptive ckoire and actual prescription? (3) Are contraceptive choices linked to some extent to sexual histories? (4) Are the contraceptive histories of the “choosers” comparable? Efforts to use available data, currently existent or rapidly being accumulated in the many United States family planning services and facilities where cytologic examinations are now routine, are fraught with hazards. Accurate information regarding all of the above questions is usually not available in clinic records. As to the first question, careful measurement of prior cytology history is difficult and costly when large and varying portions of the study groups receive medical care (which may include pelvic examinations and Papanicolaou sme;lrs) outside of the family planning facilitv data source and when the regulation method used is associated with differcrtrials in either return rates or medical
attentiveness at examinations. Are pill, IUD, and diaphragm users equally likely to have had Papanicolaou smears within, say, the two years prior to their initial visit to the birth control clinic? The twofold differences in apparent relative risk in the New York data could easily be accounted for in this manner, as pointed out by Dunn.’ The groups of “selectors” no doubt include women who are indecisive about their method of choice and who are persuaded by counselors or prescribed methods for reasons which could well be indirectly linked to cytologic abnormalities. Given a sufficiently large proportion of indecisives, this could be a serious problem. How frequently would a multiparous, unmarried, and coitally active woman-if undecided-be persuaded to use a diaphragm or a nulliparous, unmarried, and sexually active woman be persuaded to use an IUD? Both groups are likely to be assigned steroids and may show sizable relati1.e risks in their prevalence of abnormal cervical cytology. How frequently do the clinics’ interests determine prescription. and
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among what kinds of women are these most likely to be expressed? Even among those whose decisions are not influenced by clinic personnel, some association may exist between sexual history and method selected. Replicated case-comparison group studies show that the cervical cancer case woman is much more likely than a woman from a control group to have begun coitus at an early age and to have had multiple partners. Is it not also possible that coital history and coital expectations may intervene in the selection of a method to regulate fertility? Dubrow and associates’ disclosed findings based on 40,000 New York women which strongly suggest that demographic factors important in the epidemiology of cervical cancer are also correlates of contraceptive choice. The demographics are also quite likely to predict some facets of sexual behavior. However, sex history interviews are seldom obtained in clinical situations where these data can be pooled with cytology. Last, adequate contraceptive histories are rarely obtained in any setting as Melamed remarked : “Virtually all women coming to the centers (except the very young) give a history of using some type of contraceptive previously . . . although they often could not recall for how long or when. . . . Thus, even the newcomers . . . include a very significant proportion of steroid ‘choosers’ who were actually ‘users’ before they came.” With both the New York and Los Angeles studies, prior experience with methods of birth control played a prominent part in the analysis. In the New York study, the “prevalence” rates were described by number of previous years of use reported. From the data presented, one can calculate the screening rates among women who were choosing pills or diaphragms, but it is not possible to know how many new choosers had prior experience with other methods. In the Los Angeles report, the population was defined by grouping those women who had never used the pill with those who were new to any method. An unspecified number apparently reported previous use of some other methods. Women new to any method
Contraceptive
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were not considered as a separate group for contrasts. In the present study the cervical cytology results among a group of contraceptive choosers with no recent history of contraceptive use showed a small but slightly higher rate of atypicality in IUD choosers than in pill choosers. When those patients who had a “suspicious” or “positive” cervical smear (i.e., the more severe degrees of atypicality) were excluded from the tabulations, the effect was to further decrease the rate of atypicality in IUD choosers, but the differences remained small. The data in Table II are somewhat comparable to those reported by Stern and coworkers7 ; the populations appear to be demographically similar, they were defined in the same way in terms of contraceptive history, and the data were collected at about the same time. However, the differences in prevalence rates of cervical cytologic atypicality among choosers in this report are not as striking as those suggested by the Los Angeles study, where differences in “dysplasia” rather than “atypicality” were reported. Stern and associates found “dysplasia” in 83 per 1,000 pill choosers and in 5 1 per 1,000 IUD choosers ( 1.6 to 1.0)) while our “atypicality” rate was 191 per 1,000 in pill choosers, and 174 per 1,000 IUD choosers ( 1.1 to 1.0). There can be no doubt that the classification of abnormality in the two studies varies, and the authors wish to stress that these differences in reporting impose decisive limitations on comparability with respect to presumed cancer precursors. The proportion of readings in this report which are consistent with the definition of dysplasia of Stern and colleagues is not presently known, though the authors assume that “dysplasia” in the Los Angeles data overlaps considerably what we term “atypical.” In the New York data, Melamed and his group worked with a far more restrictive designation of abnormality than did Stern and associates. From the data of Melamed and colleagues it can be calculated that these rates were 5.6 per 1,000 among the oral
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contraceptive group and 3.4 per 1,000 among diaphragm users of less than one year’s duration of use ( 1.65 to 1.00). The cytologic smears in the present study were evaluated by three successive cytopathologists during the period 1969 to 1971, though most (approximately 60 per cent) were read by the third. Results shown in Fig. 1 reveal that there was some change in the proportion of women choosing pills during this time. However, even if criteria for “atypicality” changed, one might assume that the reports were proportionately distributed among the contraceptive categories. In general this was true. The time trends in rates indicate a steadily rising rate of atypical cytology reading for both IUD and oral contraceptive choosers. The figure suggests three fairly distinct time periods with respect to differences between the two groups: ( 1) 6 to 8 months where the rates were about equal with slightly more pill “atypical classifications,” (2) 8 to 10 months when IUD rates were slightly lower, and (3) 10 to 12 months when pill rates were somewhat lower. Discussions with the present cytopathologist indicated that although there may have been some changes in interpretation of cellular findings among the cytopathologists these should have been consistently applicable to all groups during each of the three periods when different individuals were responsible for cytologic reports. The reasons for the over-all rising rate of atypical cytology and the slight differences by method choice are not clear. They may reflect: ( 1) a real increase in the prevalence of infectious agents in the population, (2) changes in cytologic interpretation, and/‘or (3) time trends in patient demographic characteristics, particularly age and parity. Each of. these topics may be further investigated for a later report. Conclusion The classical papers on the epidemiology of crrvical cancer have noted that this pathology is associated with sexual dynamics. including most prominently an early age at
August 15, 1973 Am. J. Obrtet. Gynecol.
first coitus and a multiplicity of partners3 The Los Angeles and New York prevalence data suggested to us that women who select the pill may have a sexual history different from IUD and diaphragm choosers despite their apparent demographic similarity or the use of statistical matches employing demographic variables. The population described in this paper does not show comparable differences when rates of atypicality are contrasted. The coital frequency of women on the pill and IUD is reported to be similar.‘” Other patterns of sexual behavior are not known to relate significantly to method of birth control,ll but there is a paucity of data available on this topic. If screening rates of cervical cellular atypicalities are indicative of coital history factors (and this may be questioned), then the cytologic findings of the present investigation (Tables I and II) are consistent with the notion that sexual history (e.g., age at first intercourse and multiplicity of coital partners) does not play an important role in choices between the pill and the IUD. However, this investigation, like others, did not include the verbal measurement of relevant coital history variables in the clinic interview. These measurements are clearly required in order to assess relationships more directly between contraceptive choice and cervical cytology. The authors are inclined to conclude that past contraceptive use may be implicated in a complex way in the over-all prevalence or screening rates of cervical atypias between choosers of different methods of contraception (Table III). The relationship between initial screening cytology and contraceptive history may reflect sexual patterns as well as mechanical or pharmacologic effects of contraceptives. The present study leaves unanswered all questions concerning whether or not use of any method causes, precipitates, or is indirectly associated with cytologic atypicality (and vice versa). It does underscore the need for inclusion of behavioral variables, complete contraceptive histories, Papanicolaou screening histories, and assessments of
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clinic biases in the prescription of contraception as prerequisites to the analysis of prevalence rates of abnormal cervical cytology. These data are not likely to be found in birth control clinics in the absence of a specific protocol for investigating contraception as a predicator variable. Further analysis is now under way on the data reported here, and preparations are being made by the second author and a project staff for the analysis of the screening data from a large, ten-center prospective study.6 Detailed cytologic data are now being obtained in order to make assertions about the relationship between contraception and specific levels of cervical atypicality. The study combines case-comparison group and cohort methods. Clinic interviews include detailed measures of contraceptive history and behavioral variables as well as interview and chart data pertinent to prior Papani-
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colaou smears and the assessment of patientphysician roles in method selection. In order to assess the relative rates of abnormal cervical cytology among choosers of different methods of birth control, a larger number of women with no reported contraceptive history (as well as an even larger group with various histories) will be identified as they enroll in the program of gynecologic followup. Prevalence rates of abnormal cytology may then be described by method chosen as the cohort is defined. That presentation should prepare some of the groundwork for subsequent descriptions of incidence rates among the different groups of contraceptors. The authors wish to acknowledge the programming and tabulation aid afforded by Mr. Jerry Weiland and Ms. Bonnie Morel Edington. The authors are indebted to Dr. Irene Koprowska for critical review of the manuscript and useful suggestions.
REFERENCES
1.
2. 3. 4.
5. 6.
Dubrow, H., Melamed, M. R., Flehinger, B. J., Kelisky, R. P., and Koss, L. G.: Obstet. Gynecol. Survey 24: 1012, 1969. Dunn, J. E.: Br. Med. J. 4: 302, 1969. Martin, C. E.: Am. J. Public Health 57: 803, 1967. Melamed, M. R., Koss, L. G., Flehinger, B. J., Kelisky, R. P., and Dubrow, H.: Br. Med. J. 3: 195, 1969. Melamed, M. R.: Br. Med. J. 4: 302, 1969. Merritt, C. G., Balm, H., Hontz, A., and Mausner, J. S.: J. Reprod. Med. 8: 175, 1972.
7.
a. 9. 10.
11.
Stern, E., Clark, V. A., and Coffelt, C. F.: Science 169: 497, 1970. Stern, E., Clark, V. A., and Coffelt, C. F.: Am. J. Public Health 61: 553, 1971. Stern, E., Clark, V. A., and Coffelt, C. F.: Obstet. Gynecol. Survey 26: 537, 1971. Westoff, C. F., Bumpass, L., and Ryder, N. B.: Med. Aspects Human Sexuality 5: 72, 1971. Zelnik, M., and Kantner, J.: Final Report to Commission on Population Growth and the American Future, June, 1972.
J.
choice and cervical cytology
SHULMAN,
GARY
MERRITT,
Philadelphia,
Pennsylvania
M.D.,
M.P.H.
PH.D.
The prevalence rates of atypical cervical cytology among two groups of contraceptive choosers were determined. Choosers of the intrauterine contraceptive device (IUD) and the oral contraceptive pill with no reported history of contraceptive use and choosers of the IUD and pill with a prior history of use of methods of contraception other than the pill were found to have small differences in screening rates of cervical cytologic atypicality. When the cervical cytology atypicality rate is described by both current and past reported methods of birth control, it is evident that contraceptive history is associated with differential rates of cervical cytology atypicality among choosers and that any comparison between choosers should control for past use of all major methods of birth control. The similarity in atypical cervical cytology rates may reflect a similar sexual history in IUD and pill choosers, but a study which includes more specific cytologic designations and detailed measures of contraceptive history and behavioral variables is necessary to evaluate this hypotheses. A prospective study which includes these variables in evaluating the relative rates of atypical cervical cytology among choosers of various methods of birth control is described.
UNTIL RECENTLY, there has been little evidence indicating whether choosers of specific contraceptives differ in their rates of atypical cervical cytology prior to their contraceptive choice. However, Stern and associates? reported, in 1970, that within a group of Los Angeles family planning patients who had not previously used oral contraceptives those who chose the pill had a
higher prevalence of cytologic dysplasia at the time of choice than women who chose the intrauterine contraceptive device (IUD), though both groups of women were similar in demographic characteristics.’ Earlier, Melamed and colleagues”, B had presented New York family planning clinic data from which it could be shown that among women were just beginning the use of who diaphragms as compared to those beginning oral contraceptives the latter were at greater risk of cervical dysplasia and more advanced forms of abnormal cervical cytology. These findings occasioned some surprise. An editorial note appended to a summary of the article by Stern and co-workers’ raised the question: “. . . what in the world can it be that makes pill selectors have a greater likelihood of dysplasia or carcinoma in situ than do diaphragm users in New York and IUD users in California?” Needless to say, the findings are of considerable interest in evaluating the subsequent incidence of abnormal cervical cytology in women who continue methods over a period of time.
From the Department of Obstetrics and Gynecology, ‘Temple University Health Sciences Center and the Institute for Survey Research and the Department of Sociology, Temple University. The collection of data for this paper was supported in part by OEO Grant CG 8250 to the Population Council and OEO Grant CG 2810 to the American Public Health Association. The collation and analysis were supported by the National Institutes of Health. Contract No. NIH-71-2299. ’ 1 Received for publication October 1972. Revised February 5, 1973. Accepted February 15, 1973. Reprint requests: Dr. C. Gary Institute for Survey Research, University, Seltzer Hall, 1710 St., Philadelphia, Pennsylvania
23,
Merritt, Temple N. Broad 19121.
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Implications and questions raised by these findings elicited the present study. We undertook to determine the cervical cytology characteristics at the time of contraceptive choice among a group of women attending a family planning clinic in Philadelphia, and we explicitly controlled for contraceptive history. We sought to compare atypicality rates among women who reported that they had not used contraceptives for at least two years with rates among women who did report use of specific contraceptives in that period. The findings, some interpretations, and pointers for future research are presented. Methods
and
August
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material
Temple University Health Sciences Center (TUHSC) is located in a predominantly black. low socioeconomic area of North Philadelphia. Women who use this family planning program are either postabortal and postpartum inpatients or outpatients who request family planning services. At the present time, most contraceptive acceptor patients receive their initial medication and/or devices as inpatients or by referral from various community groups. The different contraceptive methods available and their side effects and efficacy are explained to each patient by a specially trained. indigenous Family Planning Counselor, and the patient’s choice is then noted on her prenatal record or on her outpatient chart. A medical history is taken and an examination performed by a resident physician. A Papanicolaou test is done and, providing tilere are no contraindications, the patient is given the rnethod and/or device of her choice. If she is an inpatient, the method of choice is provided in the hospital; if she is an outpatient, the method is provided at the time of her visit. A small, undetermined percentage of the patients are denied their choice by the physician. This information cannot be retrieved from the files rind so the patients described in this report include a few whose method was different from their choice for medical rea-
Am.
J. Obstrt.
15, 1973 Gynecol.
sons and some whose %hoice” rested upon clinic personnel recommendation. Following her acceptance, that patient sees the counselor who fills out the National Center for Health Statistics form for the visit. This interview includes an item on contraceptive history during the “past two years.” An undetermined number of women may have used some method prior to the two years, though we estimate that this was a small number in view of the relatively young ages. The data here are reported as indicating a complete contraceptive history, and the reader should bear in mind this constraint in measurement. Since 1967, a computerized file has been compiled on the cytologic specimens read at TUHSC and on the histologic reports received by the Department of Obstetrics and Gynecology. Cytology classifications were recorded with a simple system of designation : negative, atypical, suspicious, and positive. In 1969, the Family Planning Project was begun. Since then, demographic information on these patients has been recorded on the National Center for Health Statistics Provision Report Form for Family Planning Services. A master file was created and has been kept at our computer center for (family planning) reporting and administrative purposes. All patients seen for the family planning program receive a unique number, and this number is also used to identify any ancillary service, such as the Papanicolaou smear, and any subsequent histologic examination. A program was written to collate the family planning and cytology-pathology tapes, and the data presented in this report were obtained by programming and tabulating variables from the combined tape. Results
In the December, traception Of these. had used last two
period November, 1969, through 1971, 5,343 women seeking conwere examined and interviewed. 2,352 women indicated that they no contraceptive method within the years. Papanicolaou results were
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Contraceptive
Table 1. Demographic contraceptive choosers
characteristics Method
Demographic category Ethnicity White Nonwhite Education <9 29 Income < $25 week 2 $25 week Age < 18 18-23 > 23 Parity 0 >: _.
Total
1
(No.
Pill = 1,204)
%
1 Ay$$al
and
rates
of
of contraception (No. r.
IUD =
atypical
and
cytology
cervical
among
cytology
1081
new
chosen
304) / A?.$71
(No. %
Other =
431)
(No.
Total = 1,939)
/ Atj$;al
%
1 Ay$i;al
6.7 93.3
13.6 19.1
7.2 92.8
4.6 21.3
3.9 96.1
23.5 17.2
6.2 93.8
13.3 19.0
35.6 64.4
17.7 19.4
39.8 60.2
22.3 18.6
41.8 58.3
16.1 18.3
37.7 62.4
18.1 18.9
74.0 26.0
18.5 19.5
80.3 19.7
19.7 21.6
76.6 23.4
16.7 19.8
75.6 24.5
18.3 19.5
33.4 49.4 17.2
15.4 20.8 18.8
33.9 43.8 22.4
15.5 21.0 25.0
16.2 41.1 42.7
17.1 17.5 17.4
29.7 46.7 23.7
15.7 20.2 19.”
17.8 52.3 29.9 100.0
16.4 16.8 23.3 18.7
7.2 53.6 39.1 100.0
9.1 19.0 23.5 20.1
6.5 35.3 58.2 100.0
14.3 13.8 19.9 17.4,
13.6 48.7 37.7 100.0
15.5 16.7 22.2 18.6
retrieved on 2,304 of these patients, of whom 1,939 elected to use pills, an IUD, or “other methods” of contraception (diaphragm, foam, tubal ligations), while 365 elected no method. Table I pertains to the 1,939 new acceptors who reported no recent use of any method of birth control. It presents a description of basic population demographic characteristics and the screening rates of Papanicolaou smears by demographic categories. Our cytology laboratory used the cytologic descriptions “negative, ” “atypical” (apparently benign ) , “suspicious,” and “positive.” The “suspicious” category includes those classified by the Papanicolaou system as III, plus a category called “mild to moderate dysplasia.” “Positive” includes those classified as Papanicolaou Class IV and V. In this series, the atypical cytologic grouping includes all smears Pap II and above. The bottom row of Table I (Total) shows the over-all screening rates of atypicality by categories of method selected. Also shown are the distributions of patients in each selector group by
-
demographic categories and, within each demographic status, the rate of atypical cytology. The new acceptors are 94 per cent nonwhite; 38 per cent have less than a ninthgrade education; 76 per cent fall in the lower income group; 30 per cent are 18 years old or less; and 14 per cent are nulliparous. Demographic distributions by method selected show certain small differences between the groups. We wish to focus on the oral contraceptive and the IUD groups where, for example, oral contraceptive users are slightly more likely to be black (93.3 versus 92.8 per cent), somewhat better educated (35.6 and 39.8 per cent, respectively, have no high school education), of higher income (26.0 versus 19.7 per cent), younger (17.2 versus 22.4 per cent are over 23), and decidedly more likely to be nulliparous (17.8 versus 7.2 per cent). Parity is the only variable which reveals sizable differences between the two groups; in other respects they are quite similar. Atypicality within these groups fails to
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Table II. Demographic characteristics and rates of atypical cytology contraceptive choosers who have not previously used oral contraceptives Method Pill (No. = 1,434) Atypical
Demographic categorier
of contraception
Other (No. = 712) Atypical
(%)
70
(%)
70
13.3 19.5
7.2 92.8
L2.7 17.8
4.1 95.9
33.3 66.7
18.4
24.9 75.1
18.9 16.9
37.7 62.3
73.0 27.0
18.3
78.5 21.5
17.7 16.5
29.6 49.5 20.9
15.3 20.9
14.9
13.9 21.4 16.0
16.7 47.9
15.4 17.3
35.4
23.3
Ethnicity 6.8 93.2
Education <9 29 Income < $25 week 2 $25 week -he <
18 18-23
> 23 Parity 0 Total
__-
chosen
IUD (No. = 873) Atypical
70
White Nonwhite
among
100.0
19.5
21.1
20.4
19.1
32.1 53.0 4.9
28.5 66.6 100.0
show any notable pattern of differences. Over all, IUD choosers appear to be at a slightly greater risk: 20.1 versus 18.7 per cent. This difference ( 1.4 per cent) can be largely accounted for in terms of the different distributions of the groups in the categories of parity. Interestingly, at higher parity the groups are at almost identical risk (23.3 versus 23.5 per cent). The larger differences (for example, white rates of 13.6 and 4.6 per cent, respectively) are regarded as unreliable due to small numbers, e.g., one case among 22 choosers of the IUD. These findings are based on new acceptors. What occurs when the population is enlarged to include women who report previous use of nonsteroidal contraception? In the ios Angeles study the criteria for inclusion were i‘ . that the women are new to the family planning program and that they have not used the contraceptive pill.“S Similarly, the New York data probably included as pill selectors xvomen who were changing to it from other methods. Table II shows the results of this amplification of the selector population to 3,019 patients. Note that the gradient of risks now shifts toward pill selectors: 19.1 versus 17.4 per
11.6 16.5 18.2 17.4
Total (No. = 3,019) Atypical %
(%I
9::;
14.2 18.9
19.1
31.9 68.1
18.7 18.6
77.4 22.6
19.1 19.0
75.6 24.4
18.3
11.5 35.7
22.0 16.9
21.1 41.2
20.2
52.8
20.0
37.7
18.5
5.9
14.3 15.8
10.8 37.3
14.8 16.9 20.7
26.7 67.4 100.0
(%!
20.7 19.0 19.0
20.8 19.1
51.9 100.0
19.5 15.9
18.6 -
cent of the IUD selectors (Total). Again, however, the differences are small. The overall rates of atypicality for the populations of Tables I and II are identical: 18.6 per cent. This means that previous users of nonsteroidal methods have the same rates as previously noncontracepting women but that previous non-oral contraceptors who change to the pill are at greater risk than those who retain or change to IUD’s, In pooling the two populations, the IUD group appears to have received proportionately more of the better educated (60.2 per cent in Table I to 75.1 per cent in Table II) ( the older (22.4 to 53.0 per cent), and the multiparous (39.1 to 66.6 per cent). Distributions of ethnicity and income were largely unchanged. The sizable increase in the proportion of IUD users with two or more children was accompanied by a lessening of the rate of atypical classifications in this category, while pill proportions remained constant. The breakdown of rates by primary method used during the previous two years is shown in Table III. Here, column totals show that among women newly choosing or reaffirming previous contraceptive choices
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Contraceptive
Table III. Rates of atypical cervical cytology; past and current methods of contraception Present
contraceptive
Pill
Past contraceptive Pill IUD
Other contraceptive No contraceptive Total
Total (No.)
AtyPical ( (No.)
1,085 108 1’2 1,204
216 22 27 “25
2,519
490
prevalence
among
Total (No.)
19.9 207 20.4 524 45 22.1 304 18.7 19.5--~_- 1,080
there are small differences. Pill, IUD, and diaphragm choosers show rates of 19.5, 18.0, and 18.6 per cent, respectively. Notice, however, that the row totals show more sizable differences. Past IUD users (16.2 per cent) and users of other methods (24.0 per cent) represent the extremes, with “no contraceptives” (18.6 per cent) and pill (19.5 per cent) as the intermediates. Within Table III one of the more interesting observations is the relatively high rate of atypical cytology contributed to the pill chooser group by women with a past history of use of IUD’s (20.4 per cent) and other methods (22.1 per cent). Among current pill choosers, women who are continuing with pills (19.9 per cent) and those who report no contraceptive history (18.7 per cent) show lower rates. Patients who are continuing with IUD’s (15.1 per cent) have the lowest rates of any of the twelve subgroups. Table III shows that the effect of the inclusion of 746 previous IUD users and 334 “others” is to add to the pill choosers (in Table II ) proportionately more atypical cytology and so slightly raise the rates in this group. The net result is to shift the higher prevalence of cervical cytology atypicality from IUD choosers to pill choosers by adding those wth a history of using methods other than the pill. In summary, if there was no recent history of contraceptive use, there was little difference in the over-all prevalence of cervical cytologic abnormality in IUD and pill choosers. Impressions gained from Tables I,
Atypical (No.) 42 79 12 61 194
cervical
4,653
cytology
patients
1083
by
choice
IUD AtyPical rate (75)
and
AtvPical rate (76) 20.3 15.1 26.7 20.1 18.0
Other
contraceptive
Total (No.)
ical (No.)
342 114 167 431 1,054
60 20 41 75 196
17.5 17.5 24.6 17.4 18.6
Total
1,634 746 334 1,939 4,653
318 121 80 361 880
19.5 16.2 24,.0 18.6 18.9
II, and III reinforce the notion that contraceptive history is associated with different rates of atypical cervical cytology and that any contrast of rates between choosers should control for past use of all major methods of birth control. It should be recalled that the patients in this population were seen over a 26 month period of time. A perpetually vexing problem in drawing inferences from aggregate cytology data concerns shifting standards of over time, the cytologic interpretation pronounced differences between readers, and the extent to which populations can undergo rapid changes in the prevalence of infectious agents which may be reflected as an increase in rates of atypical readings of the Papanicolaou smears. With these problems in mind we sought to examine their expression in these data. In order to determine whether or not rates of ( 1) atypical cytology and (2) proportion of patients prescribed pills were constant over the 26 months, these data were examined chronologically. Fig. 1 shows a severalfold increase in the proportion of atypical reports within each of the chooser groups. The proportion of patients choosing steroidal methods remained relatively more constant, with an early decline which subsequently stabilized around 45 per cent. Comment
If we may assume standard cytopathologic descriptions, at least four specific questions should be raised in evaluating discovered differences in rates of abnormal cervical cytology among groups of contraceptive
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August 15, 1973 Am. J. Obstet. Gynecol.
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3-5
4-6
5-7
6-6
7.9
WI
llllllll I,,,,,, 911 IO-12 II-13 12-14 1315 1416 15.17 16.16 17-19 18-20 19-2, a?-22 21.23 22.~~25
l-26
MONTHS -
% STEROID
-
16 OF STEROID
CHOOSERS
-
% OF IUD CHOOSERS
CHOOSERS WITH
WITH
ATYPICAL
ATYPICAL
CYTOLOGY
CYTOLOGY
Fig. 1. The percentages of the total population choosing oral steroids and the percentages of steroid and IUD choosers with atypical cytology: 26 month time trend. choosers : (,1) Do the contraceptive groups differ in their prior experience with cervical cytologic examinations? (2) What is the relative disparity between contraceptive ckoire and actual prescription? (3) Are contraceptive choices linked to some extent to sexual histories? (4) Are the contraceptive histories of the “choosers” comparable? Efforts to use available data, currently existent or rapidly being accumulated in the many United States family planning services and facilities where cytologic examinations are now routine, are fraught with hazards. Accurate information regarding all of the above questions is usually not available in clinic records. As to the first question, careful measurement of prior cytology history is difficult and costly when large and varying portions of the study groups receive medical care (which may include pelvic examinations and Papanicolaou sme;lrs) outside of the family planning facilitv data source and when the regulation method used is associated with differcrtrials in either return rates or medical
attentiveness at examinations. Are pill, IUD, and diaphragm users equally likely to have had Papanicolaou smears within, say, the two years prior to their initial visit to the birth control clinic? The twofold differences in apparent relative risk in the New York data could easily be accounted for in this manner, as pointed out by Dunn.’ The groups of “selectors” no doubt include women who are indecisive about their method of choice and who are persuaded by counselors or prescribed methods for reasons which could well be indirectly linked to cytologic abnormalities. Given a sufficiently large proportion of indecisives, this could be a serious problem. How frequently would a multiparous, unmarried, and coitally active woman-if undecided-be persuaded to use a diaphragm or a nulliparous, unmarried, and sexually active woman be persuaded to use an IUD? Both groups are likely to be assigned steroids and may show sizable relati1.e risks in their prevalence of abnormal cervical cytology. How frequently do the clinics’ interests determine prescription. and
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among what kinds of women are these most likely to be expressed? Even among those whose decisions are not influenced by clinic personnel, some association may exist between sexual history and method selected. Replicated case-comparison group studies show that the cervical cancer case woman is much more likely than a woman from a control group to have begun coitus at an early age and to have had multiple partners. Is it not also possible that coital history and coital expectations may intervene in the selection of a method to regulate fertility? Dubrow and associates’ disclosed findings based on 40,000 New York women which strongly suggest that demographic factors important in the epidemiology of cervical cancer are also correlates of contraceptive choice. The demographics are also quite likely to predict some facets of sexual behavior. However, sex history interviews are seldom obtained in clinical situations where these data can be pooled with cytology. Last, adequate contraceptive histories are rarely obtained in any setting as Melamed remarked : “Virtually all women coming to the centers (except the very young) give a history of using some type of contraceptive previously . . . although they often could not recall for how long or when. . . . Thus, even the newcomers . . . include a very significant proportion of steroid ‘choosers’ who were actually ‘users’ before they came.” With both the New York and Los Angeles studies, prior experience with methods of birth control played a prominent part in the analysis. In the New York study, the “prevalence” rates were described by number of previous years of use reported. From the data presented, one can calculate the screening rates among women who were choosing pills or diaphragms, but it is not possible to know how many new choosers had prior experience with other methods. In the Los Angeles report, the population was defined by grouping those women who had never used the pill with those who were new to any method. An unspecified number apparently reported previous use of some other methods. Women new to any method
Contraceptive
and
cervical
cytology
1085
were not considered as a separate group for contrasts. In the present study the cervical cytology results among a group of contraceptive choosers with no recent history of contraceptive use showed a small but slightly higher rate of atypicality in IUD choosers than in pill choosers. When those patients who had a “suspicious” or “positive” cervical smear (i.e., the more severe degrees of atypicality) were excluded from the tabulations, the effect was to further decrease the rate of atypicality in IUD choosers, but the differences remained small. The data in Table II are somewhat comparable to those reported by Stern and coworkers7 ; the populations appear to be demographically similar, they were defined in the same way in terms of contraceptive history, and the data were collected at about the same time. However, the differences in prevalence rates of cervical cytologic atypicality among choosers in this report are not as striking as those suggested by the Los Angeles study, where differences in “dysplasia” rather than “atypicality” were reported. Stern and associates found “dysplasia” in 83 per 1,000 pill choosers and in 5 1 per 1,000 IUD choosers ( 1.6 to 1.0)) while our “atypicality” rate was 191 per 1,000 in pill choosers, and 174 per 1,000 IUD choosers ( 1.1 to 1.0). There can be no doubt that the classification of abnormality in the two studies varies, and the authors wish to stress that these differences in reporting impose decisive limitations on comparability with respect to presumed cancer precursors. The proportion of readings in this report which are consistent with the definition of dysplasia of Stern and colleagues is not presently known, though the authors assume that “dysplasia” in the Los Angeles data overlaps considerably what we term “atypical.” In the New York data, Melamed and his group worked with a far more restrictive designation of abnormality than did Stern and associates. From the data of Melamed and colleagues it can be calculated that these rates were 5.6 per 1,000 among the oral
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contraceptive group and 3.4 per 1,000 among diaphragm users of less than one year’s duration of use ( 1.65 to 1.00). The cytologic smears in the present study were evaluated by three successive cytopathologists during the period 1969 to 1971, though most (approximately 60 per cent) were read by the third. Results shown in Fig. 1 reveal that there was some change in the proportion of women choosing pills during this time. However, even if criteria for “atypicality” changed, one might assume that the reports were proportionately distributed among the contraceptive categories. In general this was true. The time trends in rates indicate a steadily rising rate of atypical cytology reading for both IUD and oral contraceptive choosers. The figure suggests three fairly distinct time periods with respect to differences between the two groups: ( 1) 6 to 8 months where the rates were about equal with slightly more pill “atypical classifications,” (2) 8 to 10 months when IUD rates were slightly lower, and (3) 10 to 12 months when pill rates were somewhat lower. Discussions with the present cytopathologist indicated that although there may have been some changes in interpretation of cellular findings among the cytopathologists these should have been consistently applicable to all groups during each of the three periods when different individuals were responsible for cytologic reports. The reasons for the over-all rising rate of atypical cytology and the slight differences by method choice are not clear. They may reflect: ( 1) a real increase in the prevalence of infectious agents in the population, (2) changes in cytologic interpretation, and/‘or (3) time trends in patient demographic characteristics, particularly age and parity. Each of. these topics may be further investigated for a later report. Conclusion The classical papers on the epidemiology of crrvical cancer have noted that this pathology is associated with sexual dynamics. including most prominently an early age at
August 15, 1973 Am. J. Obrtet. Gynecol.
first coitus and a multiplicity of partners3 The Los Angeles and New York prevalence data suggested to us that women who select the pill may have a sexual history different from IUD and diaphragm choosers despite their apparent demographic similarity or the use of statistical matches employing demographic variables. The population described in this paper does not show comparable differences when rates of atypicality are contrasted. The coital frequency of women on the pill and IUD is reported to be similar.‘” Other patterns of sexual behavior are not known to relate significantly to method of birth control,ll but there is a paucity of data available on this topic. If screening rates of cervical cellular atypicalities are indicative of coital history factors (and this may be questioned), then the cytologic findings of the present investigation (Tables I and II) are consistent with the notion that sexual history (e.g., age at first intercourse and multiplicity of coital partners) does not play an important role in choices between the pill and the IUD. However, this investigation, like others, did not include the verbal measurement of relevant coital history variables in the clinic interview. These measurements are clearly required in order to assess relationships more directly between contraceptive choice and cervical cytology. The authors are inclined to conclude that past contraceptive use may be implicated in a complex way in the over-all prevalence or screening rates of cervical atypias between choosers of different methods of contraception (Table III). The relationship between initial screening cytology and contraceptive history may reflect sexual patterns as well as mechanical or pharmacologic effects of contraceptives. The present study leaves unanswered all questions concerning whether or not use of any method causes, precipitates, or is indirectly associated with cytologic atypicality (and vice versa). It does underscore the need for inclusion of behavioral variables, complete contraceptive histories, Papanicolaou screening histories, and assessments of
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clinic biases in the prescription of contraception as prerequisites to the analysis of prevalence rates of abnormal cervical cytology. These data are not likely to be found in birth control clinics in the absence of a specific protocol for investigating contraception as a predicator variable. Further analysis is now under way on the data reported here, and preparations are being made by the second author and a project staff for the analysis of the screening data from a large, ten-center prospective study.6 Detailed cytologic data are now being obtained in order to make assertions about the relationship between contraception and specific levels of cervical atypicality. The study combines case-comparison group and cohort methods. Clinic interviews include detailed measures of contraceptive history and behavioral variables as well as interview and chart data pertinent to prior Papani-
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colaou smears and the assessment of patientphysician roles in method selection. In order to assess the relative rates of abnormal cervical cytology among choosers of different methods of birth control, a larger number of women with no reported contraceptive history (as well as an even larger group with various histories) will be identified as they enroll in the program of gynecologic followup. Prevalence rates of abnormal cytology may then be described by method chosen as the cohort is defined. That presentation should prepare some of the groundwork for subsequent descriptions of incidence rates among the different groups of contraceptors. The authors wish to acknowledge the programming and tabulation aid afforded by Mr. Jerry Weiland and Ms. Bonnie Morel Edington. The authors are indebted to Dr. Irene Koprowska for critical review of the manuscript and useful suggestions.
REFERENCES
1.
2. 3. 4.
5. 6.
Dubrow, H., Melamed, M. R., Flehinger, B. J., Kelisky, R. P., and Koss, L. G.: Obstet. Gynecol. Survey 24: 1012, 1969. Dunn, J. E.: Br. Med. J. 4: 302, 1969. Martin, C. E.: Am. J. Public Health 57: 803, 1967. Melamed, M. R., Koss, L. G., Flehinger, B. J., Kelisky, R. P., and Dubrow, H.: Br. Med. J. 3: 195, 1969. Melamed, M. R.: Br. Med. J. 4: 302, 1969. Merritt, C. G., Balm, H., Hontz, A., and Mausner, J. S.: J. Reprod. Med. 8: 175, 1972.
7.
a. 9. 10.
11.
Stern, E., Clark, V. A., and Coffelt, C. F.: Science 169: 497, 1970. Stern, E., Clark, V. A., and Coffelt, C. F.: Am. J. Public Health 61: 553, 1971. Stern, E., Clark, V. A., and Coffelt, C. F.: Obstet. Gynecol. Survey 26: 537, 1971. Westoff, C. F., Bumpass, L., and Ryder, N. B.: Med. Aspects Human Sexuality 5: 72, 1971. Zelnik, M., and Kantner, J.: Final Report to Commission on Population Growth and the American Future, June, 1972.