Vasectomy and the Incidence of Hospitalized Illness

0022-5347/83/1294-0760$02.00/0 Vol. 129, April

THE JOURNAL OF UROLOGY

Copyright© 1983 by The Williams & Wilkins Co.

Printed in U.S.A.

VASECTOMY AND THE INCIDENCE OF HOSPITALIZED ILLNESS DIANA B. PETITTI,* ROBERT KLEIN, HARALD KIPP

AND

GARY D. FRIEDMAN

From the Departments of Medical Methods Research and Urology, The Kaiser-Permanente Medical Care Program, Oakland, California

ABSTRACT

To determine the long-term effects of vasectomy on health we studied the incidence of hospitalized illness in 4,385 vasectomized and 13,155 age and race-matched nonvasectomized men. In none of the 16 disease groupings we examined was the incidence of hospitalized illness in the vasectomized men significantly different from that in the nonvasectomized men, considering men with all durations of vasectomy. Neither the incidence of acute myocardial infarction, other ischemic heart disease nor that of all atherosclerotic diseases considered as a group was significantly different between the vasectomized and nonvasectomized men, even in those whose duration of vasectomy was 10 years or more. These data are reassuring, providing no evidence for an adverse health effect of vasectomy mmen. The finding that vasectomy accelerates atherosclerosis in monkeys1• 2 has caused concern about the possibility of adverse effects of vasectomy on health in men. Reports thus far are reassuring. 3- 9 Herein we studied the incidence of hospitalized illness in 4,385 vasectomized and 13,155 age and race-matched nonvasectomized men to examine further the effects of vasectomy on health, We have reported previously that in this group the prevalence of a large number of illnesses and physiologic measures at the time of initial examination had no relation to vasectomy. 8 ' 9 MATERIALS AND METHODS

Our medical care program provides comprehensive medical care to about 1.8 million residents of Northern California. Since 1977 men having routine multiphasic medical checkups at the Oakland and the San Francisco facilities have completed questionnaires on which they indicate whether they have had a vasectomy and, if so, in what year the procedure was performed. We used the information from these questionnaires to identify 4,385 vasectomized men and a comparison group of 13,155 age and race-matched nonvasectomized men. The details of the matching procedure have been described elsewhere. 9 For the study subjects information on all hospitalizations in our Northern California hospitals after the examination and through 1980 was obtained from computer-stored discharge summaries, which are coded according to the International Classification of Diseases. Only the principal discharge diagnosis for each hospitalization was used in this analysis. When a man was hospitalized for a given diagnosis more than once after examination we considered only the first admission for that diagnosis. The study spanned the period when coding of hospital discharge records changed from ICDA-8 to ICD-9-CM. We used tables provided by the Commission on Professional and Hospital Activities to convert the ICD-9-CM codes to ICDA-8 codes when this was possible. A small number of hospitalization records contained unconvertible codes and these records were deleted. The denominators for the calculation of the incidence rates were determined using information from the membership records to determine in every month after an examination whether the patient was a member of the medical care program. We then cumulated the number of person-months of membership and divided by 12 to obtain person-years. The ratio of the incidence rate in the vasectomized men to the incidence rate in the controls was used to estimate relative Accepted for publication August 13, 1982. * Requests for reprints: 3451 Piedmont Ave., Oakland, California 94611.

760

risk. Ninety-five per cent confidence intervals for the relative risk estimates were calculated using the test-based method. 10 RESULTS

Table 1 shows the results of the analysis. For all of the disease groupings, except neoplasms of unspecified nature, relative risk estimates were near 1. Considering men with all durations of vasectomy, for all of the disease groupings, the 95 per cent confidence intervals for the estimated relative risk included 1 and, therefore, are not statistically significant. For all of the disease groupings the relative risk estimates were close to 1 in men with short and with long durations of vasectomy. Moreover, the relative risk estimates in the men whose duration of vasectomy was ~10 years were not greatly different from those in men whose duration of vasectomy was <10 years. Table 2 shows the incidence of some illnesses of special interest in the vasectomized and matched nonvasectomized men. The relative risks of acute myocardial infarction, other ischemic heart disease and all atherosclerotic diseases considered as a group were close to 1 and the confidence intervals were narrow. In men whose duration of vasectomy was ~10 years the relative risks of these diseases also were near 1 and the confidence intervals for the relative risk estimates were narrow. In an earlier study we found that the prevalence of peptic ulcer disease, kidney and bladder infection, joint swelling or pain, and back trouble was higher in vasectomized than in matched nonvasectomized men. 9 Table 2 shows the incidence of hospitalized illnesses that are the counterpart of these conditions. For all of them the relative risk was close to 1. However, for all of them the incidence of hospitalization was low and the 95 per cent confidence intervals were correspondingly wide. Thus, our study is not an adequate examination of the relation of vasectomy to these conditions. Table 2 also shows the incidence of hospitalization for autoimmune diseases (rheumatoid arthritis, ulcerative colitis, regional enteritis, thyroiditis and Graves' disease) in the vasectomized and matched nonvasectomized men. The incidence was too low to draw a firm conclusion about the relation of vasectomy to the incidence of autoimmune disease. DISCUSSION

This study provides no evidence for an adverse health effect of vasectomy in men. Especially important is the absence of an association of vasectomy with myocardial infarction or other manifestations of atherosclerosis. Our study included a large number of men with a long duration of vasectomy and vasectomy was not associated with atherosclerosis even in this group.

_,

TABLE

ICDA-8 Code

l incidence

ol hospitalized illn,ess

Description

and rn,atclted

Duration cf Vasectomy

Vasectmny Incidence* (No. cases)

(yrs.)

000-136

Infective and parasitic diseases

140-209

Malignant neoplasms

210-229

Benign neoplasms

230-239

Neoplasm of unspecified nature

240-279

Endocrine, nutritional, metabolic diseases

0.7 (5) (3) (2) (21) (8) (8) (6)

All <10 ~10 All <10 aa:10 All <10 ~10 All <10 a:;10 All <10

0,7 0,7 3,0 2,0 3,0 0,9 0,7 Ll 0,1 0,2 0,0 0,7 0,7 0,7

290-315

Diseases of blood and blood-forming organs Mental disorders

All <10 £10 All <10

0,7 L5 L9 2,0 L5 lLO 7,2 13,8 3,0 3,0 3,0 1L3

,;;10 320-389

Diseases of nervous system and sense organs

All <10

390-458

Diseases of circulatory system

All <10 ,;;10 All <10 £10

,;;10

460-519

520-577

580-629

680-709

Diseases of respiratory system Diseases of digestive system

All

Diseases of genitourina:ry system

All

Diseases of skin and subcutaneous tissue

780-796

Diseases of musculoskeletal system Symptoms and ill-defined conditions Accidents, poisoning and violence

(3) (4) (13) (8) (4) (77) (29) (37) (21) (12) (8)

(79)

9,9 (40)

,;;10

14,l (38) 4,0 (28) L7 (7)

<10 ~10 All <10

n

0,9 0,5 L5 3,7 3,2

Ail <10 ,;;10 All <10

(HJ)

(6) (2) (4) (26)

(13)

4,1 (11) 3,7 (26)

3,2 3,7 5,3 5,2 5,2

,;;10 800-999

(0) (5)

<10

,;;10 710-738

(3) (3) (1) (1)

(3) (2) OA (3) 0,0 (0) 0,7 (2) Ll (8)

,;;10 280-289

':-;::,:;7.·:c

'.

All <10

as:10

(13) (10) (37) (21) (14)

No ".l asectmny Incidence* {l,Jo. cases) 0,6

(13)

OA

(5) (8) (80)

l.0 3.8 2,9 (35) 5,2 (42) LO (21) 0,7 (9)

L4 (11) 0,8 (16) OA (5) L2 (10) 0,9 (19) 0,6 (7) LI (9) 0,3 (7) 0,0 (0) 0,7 (6) LB (37) LS (22) L7 (14) 3,5 (73) 2,5 (30) 5,1 (41) 10,5 (219) 6,5 (78) 16,9 (136) 2,9 (60) L7 (21) (36) 14A (302) 4,5

9,2 2L9 3,3 2,1 52 L2 L2

(111) (177) (70) (25)

IA 3,5 3,1 4,0 2,8

(11)

(42) (26)

(15) (73) (37) (32) (59)

2A (29) 3,3 (27) 4,8 (101)

5A (65) 4,2 (34)

Relativ2 Ris~c"( (95% confidence inteTval) L1 (OA, 32) L8 (OA, 7,3) 0,8 (0,2, 3,5) 0.8 (0,5, L3) 0:7 (03, L2) 0.6 (0,3, L5) 0,9 (03, 2,1) LO (0,3, 3.6) 0,8 (0,2, 2,9) 0,2 (0,1, Ll) 0,6 (0,1, 5,0)

(-,-) 0,8 L3 0.7 L3

(0,3, (0,3, (0.1, (0.3,

2,1) 0,9)

3.1) 4.9)

(-,-) LO (0.2, 5.0)

0,6 (0,3, IA) OA (0,1, L3) 0,9 (0,3, 2,6)

0.5 0,8 0,3 U U 0.8 LO L7 0,7 0,8

Ll 0,6 L2 0.8 L4 0, 7 OA U U

(0,3, LO) (OA, L7) (O,l, 0,8) (0,8, IA) (0,7, (0,6, (0,6, (0,8, (0.3, (0.6, (0,7, (0,5, (0,8, (OA, (0,8, (0,3, (O,l, (0,3, (0,7, (0,6,

L7) L2) L7) 3A) IA)

LO)

L5) 0,9) L9) L9) 2.3) L7) L6) 3A) L7)

LO 2.0) LO (0,5,

L3 L3 Ll Ll LO L2

(0,8, (0,7, 2.5) 2,3)

(0,5, (0,8, (0.6, (0.7,

LG) L6) 2.3)

* Per 1,000 person-years,

t Relative risk estimates may not equal the ratio of the 2 .incidence rates presented because the relative risks were calculated using urnounded rates. Iv1en With unknown duration of vasectomy included in calculation of the rate for all durations but excluded from the remainder of the table. TABLE 2,

Incidence of acute myocardial infarction and other diseases of special interest in vasectomized and matched nonuasectomized men

ICDA-8 Code 410

412-414

531-534

590

Description Acute myocardial infarction Other ischemic heart disease Acute n1yocardial infa.rction 1 other ischemic heart disease, arteriosclerosis, nonsyphilitic aortic aneurysm, peripheral vascular disease Peptic ulcer

Infections of kidney, bladder, urethra

Duration of Vasectomy (yrs,)

Vasectomy Incidence* (l\To. cases)

No Vasectomy Incidence* (No, cases)

A.11

3,3 (23)

<10 aa:10 All <10 £10 All <10 a:;10

1.2 (5) 6,0 (16)

2,8 (58) L8 (22)

4,1 (29) 2,7(11)

4,5 (12) 6,7 (47) 3,7 (15) 9,3 (25)

OA (3)

All <10 aa:10 All <10

0,2

0,7 0,1 0,0 0,2 0,9 0,2 L1 0,1 0,0

,;;10 710-718

Arthritis and rheumatism

Autoimmune disease

All <10 ,;;10 All <10 ,:;;10

(1) (2) (1) (0) (1) (6)

(1) (3) (1) (0) OA (1)

* Per 1,000 person-years,

4,5

3,3 2,1 5,3 5,7 3.7 9.2

(36) (69) (25)

("3) (]20) (45) (74)

0.9 (19) 0,6 (7)

u

(9)

(5) (0) OA (5) OB (16) 0,7 (9) 0,6 (5) 0,1 (3) 0,1 (1) 0,1 (1) 0,2 0,0

Relative Riskt (95% confidence interval) L2 0, 7 L3 L3 U 0.8 L2 LO LO

(C.?, (0,3, (0,7, (0,8, {0,6, (OA, (0,8, (0,6, (0,6,

0.5 OA 0,7 0,6

(0.1, 3.2) (0,1, 3,1)

LS) L6)

(0.1, L5)

(0,1, 5,0)

(-,-) 0,6 LI 0,3 L8 LO

(0,1, (OA, (0,0, (OA, (0.1,

-

(-,-)

5,0) 2.9) 2,3) 7A) 9,6)

3.0 (0.2, 4L9)

t Relative risk estimates may not equal the ratio of the 2 incidence rates presented because the relative risks were calculated using unrounded rates, 761

L9) LB) IA) L9) 2.6)

762

PETITTI AND ASSOCIATES

On the other hand, because of the small number of cases we cannot exclude an effect of vasectomy on atherosclerosis in men, such as diabetics or hypertensives, who are already at high risk of these diseases. In addition, the small numbers of hospitalized cases of autoimmune disease limit conclusions about the relation of vasectomy to these conditions. They are of particular interest because of the known relation of vasectomy with elevated titers of circulating antisperm antibodies. 10- 15 Because this study is based on self-reports some study subjects may be misclassified with respect to vasectomy. The absence of associations of vasectomy with illnesses we studied should be interpreted with the recognition that misclassification would obscure associations. Despite its limitations the study results should reassure the millions of men here and abroad who have had vasectomies. The findings join a growing body of evidence that vasectomy is safe in men. 3- 9 REFERENCES 1. Alexander, N. J. and Clarkson, T. B.: Vasectomy increases the

severity of diet-induced atherosclerosis in Macaca fascicularis. Science, 201: 538, 1978. 2. Clarkson, T. B. and Alexander, N. J.: Long-term vasectomy: effects on the occurrence and extent of atherosclerosis in rhesus monkeys. J. Clin. Invest., 65: 15, 1980. 3. Walker, A. M., Jick, H., Hunter, J. R., Danford, A. and Rothman, K. J.: Hospitalization rates in vasectomized men. J.A.M.A., 245: 2315, 1981.

4. Walker, A. M., Jick, H., Hunter, J., Danford, A., Watkins, R. N., Alhadeff, L. and Rothman, K. J.: Vasectomy and non-fatal myocardial infarction. Lancet, 1: 13, 1981. 5. Fahrenbach, H.B., Alexander, N. J., Senner, J. W., Fulgham, D. L. and Coon, L. J.: Effect of vasectomy on the retinal vasculature of men. J. Androl., 1: 299, 1980. 6. Alexander, N. J., Senner, J. W. and Hoch, E. J.: Evaluation of blood pressure in vasectomized and nonvasectomized men. Int. J. Epidemiol., 10: 217, 1981. 7. Goldacre, M. J., Clarke, J. A., Heasman, M.A. and Vessey, M. P.: Follow-up of vasectomy using medical record linkage. Amer. J. Epidemiol., 108: 176, 1978. 8. Petitti, D. B., Klein, R., Kipp, H., Kahn, W., Siegelaub, A. B. and Friedman, G. D.: Physiologic measures in men with and without vasectomies. Fertil. Steril., 37: 438, 1982. 9. Petitti, D. B., Klein, R., Kipp, H., Kahn, W., Siegelaub, A. B. and Friedman, G.D.: A survey of personal habits, symptoms of illness, and histories of disease in men with and without vasectomies. Amer. J. Public Health, 72: 476, 1982. 10. Miettinen, 0.: Estimability and estimation in case-referent studies. Amer. J. Epidemiol., 103: 226, 1976. 11. Bullock, J. Y., Gilmore, L. L. and Wilson, J. D.: Autoantibodies following vasectomy. J. Urol., 118: 604, 1977. 12. Hunter, J., Logan, H. and Greer, G.: Incidence of sperm antibodies before and after vasectomy. J. Clin. Path., 29: 1127, 1976. 13. Ansbacher, R.: Sperm-agglutinating and sperm-inlmobilizing antibodies in vasectomized men. Fertil. Steril., 22: 629, 1971. 14. Ansbacher, R.: Vasectomy: sperm antibodies. Fertil. Steril., 24: 788, 1973. 15. Shulman, S., Zappi, E., Ahmed, U. and Davis, J. E.: Immunologic consequences of vasectomy. Contraception, 5: 269, 1972.