Norplant implants and cardiovascular disease

Abstract

A 1995 publication on serious adverse events in users of Norplant implants submitted to the Food and Drug Administration's MedWatch Spontaneous Reporting System reported 14 hospitalizations for stroke in Norplant users. This number was higher than expected. This is a report on the association of current use of Norplant implants with stroke and myocardial infarction (MI) based on a pooled analysis of data from two population-based, case-control studies conducted in the US. All data collection for these two studies occurred after approval of Norplant implants for marketing in the US in December 1990. The methods of the individual studies are detailed in prior publications.

PIP: A 1995 publication submitted to the US Food and Drug Administration's MedWatch Spontaneous Reporting System in 1995 identified 14 hospitalizations for stroke in US Norplant contraceptive implant users. This paper reports the findings of a pooled analysis of data from two large population-based case-control studies conducted in California and Washington. Of the 518 stroke patients and their 1547 healthy controls, only 1 stroke patient, 1 ischemic stroke patient, and 3 controls were current Norplant users. After adjustment for age, the odds ratio (OR) for stroke in current compared with noncurrent users of Norplant was 1.0 (95% confidence interval (CI), 0.1-9.2). In addition, 307 myocardial infarction patients and their 1048 controls were available for analysis. Of these, 1 case and 1 control were current users of Norplant. The age-adjusted OR for myocardial infarction in current compared with noncurrent Norplant users was 3.5 (95% CI, 0.2-56.5). The low prevalence of Norplant use in these studies, combined with the rarity of cardiovascular events in women of reproductive age, limited the statistical power of the pooled analysis to determine whether Norplant use increases, decreases, or has no effect on the risk of cardiovascular disease.