Spontaneous superficial venous thrombophlebitis: does it increase risk for thromboembolism? A historic follow-up study in primary care.

OBJECTIVE: To determine the risk of arterial and venous complications after a spontaneous superficial venous thrombophlebitis (SVTP) in the leg in a general practice population.

STUDY DESIGN: Retrospective cohort study (LOE: 2b [CEBM]). Exposure consisted of the diagnosis of SVTP of the lower limbs on an index date. The exposed cohort was compared with an (unexposed) cohort of practice-, age-, and sex-matched controls without SVTP.

POPULATION: Patients with spontaneous SVTP in the leg were identified through diagnostic coding in the medical registers of 40,013 patients, enlisted with 5 health centers in Amsterdam, The Netherlands.

OUTCOMES: Primary outcomes were deep venous thrombosis (DVT), pulmonary embolism (PE), acute coronary events, or ischemic stroke over a 6-month follow-up period. Odds ratios (OR) were used to quantify the associations between SVTP and outcome events.

RESULTS: No statistically significant odds ratios were found for PE, coronary events or stroke. DVT was the only primary outcome to show a significant relationship. DVT occurred in 2.7% of all SVTP patients as compared with 0.2% in the controls (OR=10.2; 95% confidence interval [CI], 2.0-51.6). When controlling for prior history of DVT, the OR decreased to 7.1 and the confidence interval crossed 1.0 (95% CI, 0.9-65.6).

DISCUSSION: Spontaneous SVTP in the leg is a risk factor for DVT, but is less predictive in patients with prior DVT. Although effective treatments for the prevention of DVT are available, the absolute risk is too low to advocate prophylaxis in a general practice population. More research on prophylaxis is needed to stratify these patients at risk.