Capture-recapture and anti-tuberculosis drug prescriptions, Balearic Islands, Spain, 2010–2012

SETTING: Tuberculosis (TB) control requires accurate knowledge of TB incidence, but few studies have been published on TB incidence using individual data from drug prescriptions. OBJECTIVE: To measure the estimated completeness of regional surveillance system data before and after adding data from anti-tuberculosis drug prescriptions. DESIGN: We compiled data on all individuals who received specific anti-tuberculosis drugs from three sources-the passive surveillance system, the active surveillance system and the anti-tuberculosis drug prescription database-in the Balearic Islands, Spain, between 2010 and 2012. We applied the capture-recapture method to measure completeness of data reporting. Statistical significance was set at P < 0.05, and 95% confidence intervals (CIs) were calculated. RESULTS: We detected 605 incident cases, compared with an estimated incidence of 719 cases (95%CI 646-793), representing 84.1% data completeness. We detected 480 of an estimated 559 pulmonary TB cases (95%CI 501-617; 85.9% data completeness) and 125 of an estimated 161 extra-pulmonary TB cases (95%CI 113-211; 77.6% data completeness). CONCLUSIONS: By adding a new source, we increased detection with respect to a previous study by 10.4% for all forms of TB, 9.7% for pulmonary TB and 13% for extra-pulmonary TB.