[Epidemiological surveillance of pulmonary tuberculosis treated at the specialized care level based on 2 data sources, Valladolid; Spain].

BACKGROUND

Pulmonary tuberculosis is still more frequent that it should be in Spain given the degree of Spain's social and healthcare-related development. Apart from some individual studies, such as the Multicenter Tuberculosis Research Project, the incidence of tuberculosis is known by way of the Compulsory Notifiable Disease System, in which some degree of under-notification has been detected. The question has been raised as to whether this data can be improved through the additional use of another registry, specifically the Minimum Basic Data Set (MBDS).

METHODS

This is a retrospective study referring back to the 1996-2000 period conducted on the population of a healthcare district totaling 220,572 inhabitants. The data from the Compulsory Notifiable Disease registry was used to the specialized care level, and that of the MBDS registry for the diagnosis of pulmonary tuberculosis. The incidence rates were calculated for each source by the capture-recapture method. An analysis was made of epidemiological characteristics such as age, gender, place of residence, bacillus in sputum and treatment data on the hospitalized cases, such as average length of stay, type of admission, type of release, clinical department, HIV co-morbility.

RESULTS

The mean annual incidence recorded at the specialized care level was 16.6 cases/100,000 inhabitants in the Compulsory Notifiable Disease registry; 20.4 cases/100,000 inhabitants in the MBDS registry, and 23.1 cases/100,000 inhabitants combining both of these two sources. The incidence estimated using the capture-recapture method was that of 24.4 cases/100,000 inhabitants (IC95%: 23.5-25.3).

CONCLUSIONS

Any information system which provides reliable data serves to improve epidemiological surveillance even though it may have been designed for a different purpose. It is all a matter of knowing the limitations and unique aspects thereof. The MBDS provides information of epidemiological interest which is not included in the Compulsory Notifiable Disease reports. Using the capture-recapture method is one alternative for estimating truer pulmonary tuberculosis rates.