Objectives: To describe anti-tuberculosis drug consumption in Spain for the period, 1985-1995, compare the associated time trend and geographical pattern against case reports of tuberculosis (TB), and estimate the number of persons undergoing anti-tuberculosis therapy in 1995.
Methods: The official Drug Database was used to ascertain consumption of anti-tuberculosis drugs (isoniazid, rifampicin, pyrazinamide and ethambutol) in Spain during the period, 1985-1995. The technical units of measurement used for comparison purposes were daily defined dose (DDD) and DDD rate per day per 100,000 population. Annual trends and geographical patterns of consumption were plotted. The respective numbers of persons treated in 1995 with each of the four drugs were first estimated and then compared against TB case reports.
Results: There was an overall decline in the consumption of isoniazid, rifampicin and ethambutol over the period, 1985-1995, though the former two registered rises in 1991 and 1992. Pyrazinamide consumption showed growth throughout the study period. The highest 1995 consumption rates were registered by Galicia, Cantabria, Asturias, the Basque Country, Ceuta and Melilla, and the lowest by the Canary Islands and Navarre. Comparisons run against TB case reports revealed a greater degree of underreporting in certain provinces. In 1995, approximately 18,858 persons (48 per 100,000 population) must be assumed to have undergone pyrazinamide therapy in Spain, indicating that the reported TB rate of 22 per 100,000 population could well represent underreporting in excess of 100%.
Conclusions: The trend in anti-tuberculosis drug consumption reflects shifts in treatment guidelines and is compatible with a rise in TB incidence in recent years. Major underreporting of TB marked by wide inter-regional and -provincial differences was in evidence. Pyrazinamide consumption is probably the best indicator for estimating minimum TB incidence.