Consequences of adult HIV infection for outpatient morbidity and treatment costs: a prospective study in a factory clinic in Tanzania

Most studies of the medical costs of HIV infection focus on the terminal stage of this chronic illness when the patients have developed AIDS or severe HIV disease and in-patient care dominates. Data are also needed on the medical costs during the prolonged phase of HIV infection preceding severe terminal illness and the effects it may have on the provision of outpatient care. The study population was derived from a cohort study of factory workers and their spouses in Tanzania. Morbidity and outpatient health services utilization are estimated for 1832 adults who on average had been enrolled for two years and utilized the study clinic. Among those who had been enrolled at least 2 years, 50 cases (HIV + since enrolment) and 150 control (HIV-until last visit) were selected, matched by age, sex and income level to estimate expenditure on drugs by HIV status. There was an increase in morbidity during HIV infection: the incidence of clinical diagnoses was 30% higher among HN-positive than among HIV-negative adults (p<0.001), HIV-infected adults also made more frequent use of the outpatient services (23% higher utilization). Estimates of essential drug costs among the subsample showed a 15% increase for HIV infected adults compared to HIV-negative adults, caused by higher use of antibiotics and other antimicrobial drugs. The overall increase in morbidity, outpatient care services utilization and essential drug use due to HIV infection was limited, as HIV prevalence in this adult population was 11%. For example, the net proportion of all illness episodes attributable to HIV infection was 3.2%. Possible biases are discussed and suggest that our findings are a minimum estimate of the effect of adult HIV infection on outpatient care costs. There is a need for more studies in different settings to assess the impact of HIV infection on outpatient care in developing countries.