False positive tests for autonomic neuropathy in HIV-infection and AIDS? Case-control-study of heart rate variation in 62 cases Autonomic neuropathy is said to be common in AIDS. In a cross section study we tested heart rate variability, a simple and sensitive test, in relation to disease severity. The expiratory-inspiratory RR-interval-ratio (RRR) was normal in HIV-infected clinically healthy persons (mean 1.45; n = 10), but progressively lowered in LAS (1.24; n = 12), ARC (1.20; n = 7), AIDS (1.13; n = 20), AIDS with pneumocystis carinii pneumonia (1.07; n = 7) and patients who died within the four month study (1.06; n = 6). The progressive decrease of heart rate variability (from 45% to 6% for group means) is in accord with previous reports. - In a simultaneous case-control study we compared RRR of these 62 patients with those of 62 not HIV infected patients matched for age, sex, resting heart rate and presence of pneumonia. Neither in the six subgroups nor in the total group we found a difference between HIV infected patients and their controls (1.20 +/- 0.18 SD and 1.22 +/- 0.17, respectively; 62 pairs). The decrease of RRR with increasing disease severity in HIV-infected patients was mainly dependent upon increasing heart rate and to a lesser degree upon increasing age. Therefore, a decreased heart rate variability in AIDS is not a specific sign of autonomic neuropathy and likely to be a false positive test result.