AIDS defining diseases in the UK: the impact of PCP prophylaxis and twelve years of change.

We examined all reports of adult AIDS cases made to the 2 national surveillance centres in the UK for changes in AIDS defining conditions between January 1982 and September 1994. Differences and changes among persons diagnosed since January 1988 who had and had not been aware of their HIV infection prior to their AIDS diagnosis were of particular interest. Pneumocystis carinii pneumonia (PCP) is the AIDS defining disease most often reported at the initial AIDS diagnosis. Its proportion of all AIDS cases has increased significantly between January 1982 and December 1987 and decreased markedly thereafter. Since January 1988 a significant decrease in the proportion of cases diagnosed with cryptosporidial infection was also observed while increases were observed in the proportion of cases diagnosed with: HIV wasting (chi(1)(2) = 5.56) PML (chi(1)(2) = 19.47), mycobacterium avium complex (chi(1)(2) = 35.76) and pulmonary tuberculosis (chi(1)(2) = 144.0). For cases diagnosed between January 1988 and September 1994, PCP was more likely to be diagnosed in patients previously unaware of their HIV infection (P < 0.01) as was extrapulmonary TB (P < 0.01). In contrast, the following diseases were more likely to be diagnosed in patients already aware of their HIV infection prior to the diagnosis of AIDS: oesophageal candidiasis (P < 0.001), HIV wasting (P = 0.07), mycobacterium avium complex (P = 0.0001), cytomegalovirus disease (P < 0.001), HIV encephalopathy (P = 0.0009) and cryptosporidial infection (P = 0.02). Prophylaxis and anti-retroviral therapy appear to have had a significant impact on the temporal changes of the most frequently diagnosed AIDS diseases. While PCP prophylaxis has substantially reduced the likelihood of a PCP diagnosis at AIDS, the corresponding increase in other opportunistic infections suggests that there may be a need for improved prophylaxis for these conditions.