Objective: Our purpose was to determine the prevalence of cocaine-associated thrombocytopenia.
Study design: This cohort study was conducted in an inner-city prenatal center. A total of 1907 patients were screened by the Mother's Project, which is an intervention project for inner-city cocaine-abusing parturients. Platelet counts were grouped by illicit drug usage.
Results: Platelet counts were available in 37% (709) of subjects; there were no differences between subjects with available platelet counts and those without on illicit drug use or other demographic measures. Five groups were defined: drug-free group (n = 331), cocaine group (n = 104), cocaine and opiates group (n = 11), opiates group (n = 18), and other-drug group (n = 236). Nineteen subjects had a low platelet count (< 150 x 10(9)/L). The medical records of all subjects with a low platelet count were reviewed for any medical condition known to be associated with thrombocytopenia, and two subjects were excluded. The rate of thrombocytopenia in the drug-free group was 1.5%, whereas the rate in the cocaine group was 6.7% (relative risk 4.4, p < 0.05). Because of the reported association of thrombocytopenia with seropositive human immunodeficiency virus status, seropositive women were excluded from the analysis. Even after human immunodeficiency virus status adjustments for the estimated rate, the cocaine-using group continued to have a significantly higher rate of thrombocytopenia (5.4% to 7.2% vs 1.23% to 1.26%, p < 0.05 to p < 0.005).
Conclusions: These results indicate that cocaine use is an independent risk factor for thrombocytopenia in an inner-city parturient population.