Fatal venous thromboembolism associated with different combined oral contraceptives: a study of incidences and potential biases in spontaneous reporting.
ABSTRACT Fatal venous thromboembolism (VTE) is a rare complication of combined oral contraceptive (COC) treatment. This study aims to determine incidences of fatal VTE in relation to the type of COC and the percentage of cases reported to the Swedish Adverse Drug Reactions Advisory Committee (SADRAC). A further aim is to compare the characteristics of reported and not reported cases.
This retrospective study is a separate analysis using data from a larger study that included women aged 15-44 years between 1990 and 1999 with VTE coded as the underlying or contributory cause of death in the Swedish Cause of Death Register. COC use within 2 months of the date of symptom onset or death was identified in 28 cases. Sales data were obtained from the National Corporation of Swedish Pharmacies. Reported cases were identified in the SADRAC database.
After excluding two cases where the type of COC was unknown, the crude incidences of fatal VTE were 5.1 (95% CI 2.3, 9.6), 8.6 (95% CI 4.3, 15.4) and 9.1 (95% CI 3.3, 19.8) cases per million women per year for levonorgestrel-, desogestrel- and norethisterone-containing COCs, respectively. Age-adjusted incidences were approximately twice as high for desogestrel- and norethisterone-containing COCs compared with levonorgestrel-containing COCs, although differences were not statistically significant. Thirty-six percent of cases were reported. Reporting was positively associated with information in medical records relevant to the VTE diagnosis that the patient was a COC user and was significantly higher in northern Sweden.
Results from this study support a higher incidence of fatal VTE with desogestrel-containing COCs than with levonorgestrel-containing COCs.
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ABSTRACT: Venous thromboembolism (VTE) is a serious complication. Large claims databases can potentially identify the effects that medications have on VTE. The purpose of this study is to evaluate the evidence supporting the validity of VTE codes. A search of MEDLINE database is supplemented by manual searches of bibliographies of key relevant articles. We selected all studies in which a claim code was validated against a medical record. We reported the positive predictive value (PPV) for the VTE claim compared to the medical record. Our search strategy yielded 345 studies, of which only 19 met our eligibility criteria. All of the studies reported on ICD-9 codes, but only two studies reported on pharmacy codes, and one study reported on procedure codes. The highest PPV (65%-95%) was reported for the combined use of ICD-9 codes 415 (pulmonary embolism), 451, and 453 (deep vein thrombosis) as a VTE event. If a specific event like DVT (PPV 24%-92%) or PE (PPV 31%-97%) was evaluated, the PPV was lower than when the combined events were examined. Studies that included patients after orthopedic surgery reported the highest PPV (96%-100%). The use of ICD-9 415, 451, and 453 are appropriate for the identification of VTE in claims databases. The codes performed best when codes were evaluated in patients at higher risk of VTE.Pharmacoepidemiology and Drug Safety 01/2012; 21 Suppl 1:154-62. DOI:10.1002/pds.2341 · 2.90 Impact Factor