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Accuracy of recall of use of an intrauterine device
Contraception
45:363-368,
ACCURACY
OF
RECALL
P. NischanI,
1992 OF USE OF AN INTRAUTERINE D.B.
Thomas'
DEVICE
and K. Ebelingl
Faculty of Medicine (Charite), Clinic for Oncology, Schumannstrasse 20-21, Humboldt University, O-1040 Berlin, Germany Fred Hutchinson Cancer Research Center, 1124 Columbia Street, Seattle, WA 98104,
USA
ABSTRACT Within a case-control study __ of the relationship . ^ . I between oral contraceptives and breast cancer, inrormation on other contraceptive practices, including use of an intrauterine device (IUD) was obtained through interviews of study subjects and from the records of gynaecologists. Information from these two sources was compared for 239 women who had ever used an IUD. The results showed that agreement on total duration, number of IUD episodes, and time since first and time since last IUD use was excellent. As approximately 75% of IUDs used were unknown, agreement on brands could not be investigated. Studies investigating the effects of individual types of IUDs should use physician records as an additional source of information.
INTRODUCTION Pelvic inflammatory disease has been investigated as a possible short-term adverse effect of the intrauterine device (IUD) (l), and cancers of the genital tract have been studied as possible long-term consequences (2,3). Retrospective studies rely largely on data from interviews, and the accuracy of recall could influence the results, particularly of studies of possible long-term consequences of IUD use. Harlow and Linet (4) have recently reviewed studies investigating recall of past medical exposures. Among the exposures mostly investigated are medications associated with female reproduction. The use of an IUD, however, has not yet been considered. This paper reports results of a comparison of data on IUD usage from interviews and physicians' records. Submitted Accepted
for publication for publication
Copyright
0
November February
26, 1991 11, 1992
7992 Butterworth-Heinemann
364
Contraception
METHODS This study was carried out within the German part (formerly German Democratic Republic = GDR) of the WHO Collaborative Study of Neoplasia and Steroid Contraceptives (5) which was designed as a multinational hospital-based case-control study to investigate the possible influence of steroid contraceptives on cancer risk at several sites (breast, uterus, ovary, liver). At this centre (6), cases were restricted to breast cancer newly admitted to the Central Institute of Cancer Research, Berlin, from November 1982 through June 1986 and born in 1930 or later. Approximately two controls per case, group matched on age, were selected from among women admitted to the ear, nose and throat, eye, orthopaedic and dermatologic wards of the Klinikum Berlin-Buch for conditions presumably not associated with steroid contraceptives. Data were obtained by interviews utilizing a German version of an original English questionnaire. Beside other known or suspected risk factors, complete information was sought for use of steroid contraceptives and IUDs as to periods of use and brand name. A calendar was used to assist in recall of periods of use. As to IUDs, photos or samples were not shown. Women who had used steroid contraceptives or IUDs, as well as those with prior breast or gynaecological operations or Pap smears, were asked to provide the names of all gynaecologists that they had consulted during their reproductive life. The gynaecologists were then sent a questionnaire to obtain detailed information on the items of interest. Of 502 eligible cases and 1316 controls selected for this study, 490 cases and 1223 controls were interviewed cases and 260 controls had ever used an IUD, (6). Sixty-one and records were obtained from the gynaecologists of 45 (73.8%) of these cases and 194 (74.6%) of these controls. The characteristics of IUD use analysed include total duration, times since first and last use, number of periods of IUD use and name of IUD used. Agreement between interviews and gynaecologists' records on IUD use was judged by the overall proportion of agreement and by means of weighted kappa (7) for categorical data or categorised continuous data. The degree of agreement beyond chance is characterized by different ranges of values for weighted kappa: values greater 0.75 indicate excellent, values between 0.40 and 0.75 good, and values below 0.40 poor agreement. The kappa statistic has been criticized when applied to continuous data (8), and the correlation coefficient therefore was also calculated for continuous variables. Unless otherwise stated, all analyses are based on data from cases and controls combined.
365
Contraception
RESULTS Table I shows the total duration of IUD use as reported by women and their gynaecologists. Agreement between these sources was within one month in 45% of the women. This increased to 80% for a difference of up to one used in Table I, agreement year. Based on the categories with weighted kappa=0.88. The correlation was excellent, coefficient (r=0.95) was highly statistically significant (p<0.001). TABLE
(months) of IUD use - comparison of I. Duration interview data and gynaecologist record data
Physician record
Subjects+ (12
Cl2 13-36 37-60 61-96 ->97
27 6 0 0 0
+ 4 subjects
excluded
13-36
37-60
5 41 5 0 0
0 9 37 3 1
61-96 0 1 3 32 4
297 0 0 1 5 55
due to WnknownW.
Regarding time since first IUD use, agreement was within one month for 49% of the women, and within one year for 79% of the subjects (Table II). Excluding current users, there was agreement within one month on time since last use in 60% of the subjects, and within one year in 80% (Table III). Again, there was excellent agreement between the two data sources with weighted kappa=0.87 for time since first IUD use and weighted kappa=0.85 for time since last IUD use. The correlation coefficients (r=0.96 in both instances) were highly statistically significant (p<0.001). TABLE
II. Time (months) since first IUD use - comparison of interview data and gynaecologist record data
Physician record
Subjects -C36
X36 37-96 97-120 121-144 >I45 -
44 5 0 0 0
37-96 6 79 4 2 1
97-120 0 2 24 3 1
121-144 0 1 5 11 5
>145 0 0 2 3 41
366
TABLE
Contraception
III.
Time (months) since last IUD use - comparison of interview data and gynaecologist record data
Physician record
Subjects+
<3 4-36 37-60 61-96 >97 + 140 subjects
<3 -
4-36
11 1 0 0 0
1 34 3 1 0
excluded
because
37-60
61-96
0 3 13 3 0
of current
297
0 1 2 9 2
0 0 0 2 13
use.
Change to a different IUD or IUD use after an interval of non-use of two or more months was considered a separate period of use. According to the medical records, 77% of the IUD users had had one, 18% two,and 5% three or more periods of IUD use. Exact agreement on number of episodes was 90% (Table IV); and there was 99% agreement within one period of use. A weighted kappa=0.79 indicated excellent agreement. Six brands of IUDs were on the market during the study period. However, women were mostly unaware of the brand as well as the type of the IUD that they had used; women were able to provide a brand for only 21% of the IUD periods of use. TABLE
IV. Number of periods of IUD use - comparison of interview data and gynaecologist record data
Physician record
1 2 3 4 >5 -
Subjects 1
2
3
4
->5
176 9 0 0 0
7 33 2 0 0
1 0 5 1 0
0 1 2 1 0
0 0 0 0 1
Agreement on duration of use, times since first and last use, and number of periods of use did not vary by marital status, place of residence, age at interview, duration of IUD use and time since last use, nor significantly by subject status (case or control). In both cases and controls, agreement within one year on total duration was 80%, on time since first use in cases 86% and in controls 77% (p-0.25), on time since last use 71% and 81% (p-0.30), and on number of periods 93% and 90% Agreement on the name of the IUD (P-0.75), respectively.
367
Contraception
increased significantly for city: 26.2%), years 29.1%) and age (highest
with place of residence (highest of education (highest for 13+: for <45: 27.6%). DISCUSSION
of At the time of the study, the estimated percentage IUD users among fertile women was 6% in East-Germany, and there were six brands on the market (9). Results of studies especially concening pelvic inflammatory disease were critically interpreted, and these authors recommended the application of an IUD when the indication had seriously been considered (9,10,11). The results of this investigation show that, with the exception of the brand name, characteristics of IUD use were recalled in close agreement with data provided by gynaecologists on the basis of their patient records. These characteristics include total duration of use, times since first and last use,and number of periods of use. Recall of these characteristics was better for IUD use than for oral contraceptive use (4). At least in part, this might be due to thorough counselling, the conscious choice of this method between child births,and the problems with the insertion or removal of the IUD. Only 25% of the women were able to provide the brand name of their IUD. Therefore, we could not compare the brand names ascertained by interview with names from medical records. There was a trend of increasing awareness of the IUD!a name with place of residence, education and age, but at best not more than 30% of the women in any group recalled the name of their IUD. Studies of specific types of IUDs should therefore include a record review to identify specific types of devices. Since photos or samples were not used, the effect of these aids remains to be shown. These results are not likely to be biased. The group of women with a validated IUD history was not appreciably different from those women whose IUD history was not validated with respect to age at interview (p-0.45), marital status (p-0.40), place of residence (p-0.55), years of schooling (p-0.40) and number of live births (p-0.55). Cases and controls had the same proportion of IUD use validated and did not differ with respect to agreement rates. In conclusion, this study showed that validity of information on IUD use from interviews is good except for brand. Though the number of cases was rather small and women with breast cancer might recall IUD use differently from those with genital tract diseases, validity of information was as good for cases as for controls so that case-control studies are not likely to give biased relative risk estimates.
368
Contraception
ACKNOWLEDGEMENTS This research received support from the Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization. We thank Jacqueline Cravaack and Ulrike Hirsch for technical assistance and manuscript preparation.
REFERENCES 1. Kronmal RA, Whitney CW, Mumford SS. The intrauterine device and pelvic inflammatory disease: The women's health study reanalyzed. J Clin Epidemiol 1991;44: 109-22. 2. Celentano DD, Klassen AC, Weisman CS, Rosenshein NB. The role of contraceptive use in cervical cancer: The Maryland cervical cancer case-control study. Am J Epidemiol 1987;126:592-604. 3. Blenkinsopp WK, Chapman P. Prevalence of cervical neoplasia and infection in women using intrauterine contraceptive devices. J Reprod Med 1982;27:709-13. 4. Harlow SD, Linet MS. Agreement between data and medical records: The evidence recall. Am J Epidemiol 1989;129:233-48.
questionnaire for accuracy
of
5. WHO Collaborative Study of Neoplasia and Steroid Contraceptives. Breast cancer and combined oral contraceptives: Results from a multinational study. Br J Cancer 1990;61:110-9. 6. Ebeling K, Ray R, Nischan P, Thomas DB, Kunde D, Stalsberg H. Combined oral contraceptives containing chlormadinone acetate and breast cancer: Results of a case-control study. Br J Cancer 1991;62:804-8. 7. Fleiss JL. Statistical methods proportions. 2nd ed. New York: 1981;223-4.
for rates and John Wiley and
Sons,
8. Maclure M, Willett WC. Misinterpretation and misuse of the kappa statistic. Am J Epidemiol 1987;126: 161-9. 9. Hagen P. Intrauterine contraception from the viewpoint of an ambulatory gynaecologic department. (In German). Z tirztl Fortbild 1981;75:800-4. 10. Neumann HG. Value of intrauterine contraception German). Z firztl Fortbild 1985;79:449-51. 11. Tauber PF. Gynakologe
Intrauterine contraception 1984;17:185-93.
(In
(In German).
45:363-368,
ACCURACY
OF
RECALL
P. NischanI,
1992 OF USE OF AN INTRAUTERINE D.B.
Thomas'
DEVICE
and K. Ebelingl
Faculty of Medicine (Charite), Clinic for Oncology, Schumannstrasse 20-21, Humboldt University, O-1040 Berlin, Germany Fred Hutchinson Cancer Research Center, 1124 Columbia Street, Seattle, WA 98104,
USA
ABSTRACT Within a case-control study __ of the relationship . ^ . I between oral contraceptives and breast cancer, inrormation on other contraceptive practices, including use of an intrauterine device (IUD) was obtained through interviews of study subjects and from the records of gynaecologists. Information from these two sources was compared for 239 women who had ever used an IUD. The results showed that agreement on total duration, number of IUD episodes, and time since first and time since last IUD use was excellent. As approximately 75% of IUDs used were unknown, agreement on brands could not be investigated. Studies investigating the effects of individual types of IUDs should use physician records as an additional source of information.
INTRODUCTION Pelvic inflammatory disease has been investigated as a possible short-term adverse effect of the intrauterine device (IUD) (l), and cancers of the genital tract have been studied as possible long-term consequences (2,3). Retrospective studies rely largely on data from interviews, and the accuracy of recall could influence the results, particularly of studies of possible long-term consequences of IUD use. Harlow and Linet (4) have recently reviewed studies investigating recall of past medical exposures. Among the exposures mostly investigated are medications associated with female reproduction. The use of an IUD, however, has not yet been considered. This paper reports results of a comparison of data on IUD usage from interviews and physicians' records. Submitted Accepted
for publication for publication
Copyright
0
November February
26, 1991 11, 1992
7992 Butterworth-Heinemann
364
Contraception
METHODS This study was carried out within the German part (formerly German Democratic Republic = GDR) of the WHO Collaborative Study of Neoplasia and Steroid Contraceptives (5) which was designed as a multinational hospital-based case-control study to investigate the possible influence of steroid contraceptives on cancer risk at several sites (breast, uterus, ovary, liver). At this centre (6), cases were restricted to breast cancer newly admitted to the Central Institute of Cancer Research, Berlin, from November 1982 through June 1986 and born in 1930 or later. Approximately two controls per case, group matched on age, were selected from among women admitted to the ear, nose and throat, eye, orthopaedic and dermatologic wards of the Klinikum Berlin-Buch for conditions presumably not associated with steroid contraceptives. Data were obtained by interviews utilizing a German version of an original English questionnaire. Beside other known or suspected risk factors, complete information was sought for use of steroid contraceptives and IUDs as to periods of use and brand name. A calendar was used to assist in recall of periods of use. As to IUDs, photos or samples were not shown. Women who had used steroid contraceptives or IUDs, as well as those with prior breast or gynaecological operations or Pap smears, were asked to provide the names of all gynaecologists that they had consulted during their reproductive life. The gynaecologists were then sent a questionnaire to obtain detailed information on the items of interest. Of 502 eligible cases and 1316 controls selected for this study, 490 cases and 1223 controls were interviewed cases and 260 controls had ever used an IUD, (6). Sixty-one and records were obtained from the gynaecologists of 45 (73.8%) of these cases and 194 (74.6%) of these controls. The characteristics of IUD use analysed include total duration, times since first and last use, number of periods of IUD use and name of IUD used. Agreement between interviews and gynaecologists' records on IUD use was judged by the overall proportion of agreement and by means of weighted kappa (7) for categorical data or categorised continuous data. The degree of agreement beyond chance is characterized by different ranges of values for weighted kappa: values greater 0.75 indicate excellent, values between 0.40 and 0.75 good, and values below 0.40 poor agreement. The kappa statistic has been criticized when applied to continuous data (8), and the correlation coefficient therefore was also calculated for continuous variables. Unless otherwise stated, all analyses are based on data from cases and controls combined.
365
Contraception
RESULTS Table I shows the total duration of IUD use as reported by women and their gynaecologists. Agreement between these sources was within one month in 45% of the women. This increased to 80% for a difference of up to one used in Table I, agreement year. Based on the categories with weighted kappa=0.88. The correlation was excellent, coefficient (r=0.95) was highly statistically significant (p<0.001). TABLE
(months) of IUD use - comparison of I. Duration interview data and gynaecologist record data
Physician record
Subjects+ (12
Cl2 13-36 37-60 61-96 ->97
27 6 0 0 0
+ 4 subjects
excluded
13-36
37-60
5 41 5 0 0
0 9 37 3 1
61-96 0 1 3 32 4
297 0 0 1 5 55
due to WnknownW.
Regarding time since first IUD use, agreement was within one month for 49% of the women, and within one year for 79% of the subjects (Table II). Excluding current users, there was agreement within one month on time since last use in 60% of the subjects, and within one year in 80% (Table III). Again, there was excellent agreement between the two data sources with weighted kappa=0.87 for time since first IUD use and weighted kappa=0.85 for time since last IUD use. The correlation coefficients (r=0.96 in both instances) were highly statistically significant (p<0.001). TABLE
II. Time (months) since first IUD use - comparison of interview data and gynaecologist record data
Physician record
Subjects -C36
X36 37-96 97-120 121-144 >I45 -
44 5 0 0 0
37-96 6 79 4 2 1
97-120 0 2 24 3 1
121-144 0 1 5 11 5
>145 0 0 2 3 41
366
TABLE
Contraception
III.
Time (months) since last IUD use - comparison of interview data and gynaecologist record data
Physician record
Subjects+
<3 4-36 37-60 61-96 >97 + 140 subjects
<3 -
4-36
11 1 0 0 0
1 34 3 1 0
excluded
because
37-60
61-96
0 3 13 3 0
of current
297
0 1 2 9 2
0 0 0 2 13
use.
Change to a different IUD or IUD use after an interval of non-use of two or more months was considered a separate period of use. According to the medical records, 77% of the IUD users had had one, 18% two,and 5% three or more periods of IUD use. Exact agreement on number of episodes was 90% (Table IV); and there was 99% agreement within one period of use. A weighted kappa=0.79 indicated excellent agreement. Six brands of IUDs were on the market during the study period. However, women were mostly unaware of the brand as well as the type of the IUD that they had used; women were able to provide a brand for only 21% of the IUD periods of use. TABLE
IV. Number of periods of IUD use - comparison of interview data and gynaecologist record data
Physician record
1 2 3 4 >5 -
Subjects 1
2
3
4
->5
176 9 0 0 0
7 33 2 0 0
1 0 5 1 0
0 1 2 1 0
0 0 0 0 1
Agreement on duration of use, times since first and last use, and number of periods of use did not vary by marital status, place of residence, age at interview, duration of IUD use and time since last use, nor significantly by subject status (case or control). In both cases and controls, agreement within one year on total duration was 80%, on time since first use in cases 86% and in controls 77% (p-0.25), on time since last use 71% and 81% (p-0.30), and on number of periods 93% and 90% Agreement on the name of the IUD (P-0.75), respectively.
367
Contraception
increased significantly for city: 26.2%), years 29.1%) and age (highest
with place of residence (highest of education (highest for 13+: for <45: 27.6%). DISCUSSION
of At the time of the study, the estimated percentage IUD users among fertile women was 6% in East-Germany, and there were six brands on the market (9). Results of studies especially concening pelvic inflammatory disease were critically interpreted, and these authors recommended the application of an IUD when the indication had seriously been considered (9,10,11). The results of this investigation show that, with the exception of the brand name, characteristics of IUD use were recalled in close agreement with data provided by gynaecologists on the basis of their patient records. These characteristics include total duration of use, times since first and last use,and number of periods of use. Recall of these characteristics was better for IUD use than for oral contraceptive use (4). At least in part, this might be due to thorough counselling, the conscious choice of this method between child births,and the problems with the insertion or removal of the IUD. Only 25% of the women were able to provide the brand name of their IUD. Therefore, we could not compare the brand names ascertained by interview with names from medical records. There was a trend of increasing awareness of the IUD!a name with place of residence, education and age, but at best not more than 30% of the women in any group recalled the name of their IUD. Studies of specific types of IUDs should therefore include a record review to identify specific types of devices. Since photos or samples were not used, the effect of these aids remains to be shown. These results are not likely to be biased. The group of women with a validated IUD history was not appreciably different from those women whose IUD history was not validated with respect to age at interview (p-0.45), marital status (p-0.40), place of residence (p-0.55), years of schooling (p-0.40) and number of live births (p-0.55). Cases and controls had the same proportion of IUD use validated and did not differ with respect to agreement rates. In conclusion, this study showed that validity of information on IUD use from interviews is good except for brand. Though the number of cases was rather small and women with breast cancer might recall IUD use differently from those with genital tract diseases, validity of information was as good for cases as for controls so that case-control studies are not likely to give biased relative risk estimates.
368
Contraception
ACKNOWLEDGEMENTS This research received support from the Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization. We thank Jacqueline Cravaack and Ulrike Hirsch for technical assistance and manuscript preparation.
REFERENCES 1. Kronmal RA, Whitney CW, Mumford SS. The intrauterine device and pelvic inflammatory disease: The women's health study reanalyzed. J Clin Epidemiol 1991;44: 109-22. 2. Celentano DD, Klassen AC, Weisman CS, Rosenshein NB. The role of contraceptive use in cervical cancer: The Maryland cervical cancer case-control study. Am J Epidemiol 1987;126:592-604. 3. Blenkinsopp WK, Chapman P. Prevalence of cervical neoplasia and infection in women using intrauterine contraceptive devices. J Reprod Med 1982;27:709-13. 4. Harlow SD, Linet MS. Agreement between data and medical records: The evidence recall. Am J Epidemiol 1989;129:233-48.
questionnaire for accuracy
of
5. WHO Collaborative Study of Neoplasia and Steroid Contraceptives. Breast cancer and combined oral contraceptives: Results from a multinational study. Br J Cancer 1990;61:110-9. 6. Ebeling K, Ray R, Nischan P, Thomas DB, Kunde D, Stalsberg H. Combined oral contraceptives containing chlormadinone acetate and breast cancer: Results of a case-control study. Br J Cancer 1991;62:804-8. 7. Fleiss JL. Statistical methods proportions. 2nd ed. New York: 1981;223-4.
for rates and John Wiley and
Sons,
8. Maclure M, Willett WC. Misinterpretation and misuse of the kappa statistic. Am J Epidemiol 1987;126: 161-9. 9. Hagen P. Intrauterine contraception from the viewpoint of an ambulatory gynaecologic department. (In German). Z tirztl Fortbild 1981;75:800-4. 10. Neumann HG. Value of intrauterine contraception German). Z firztl Fortbild 1985;79:449-51. 11. Tauber PF. Gynakologe
Intrauterine contraception 1984;17:185-93.
(In
(In German).