A retrospective cohort study was conducted to
quantitate the relationship between neutropenia
and rates of clinical bacteraemia among adults with HIV
infection receiving medical care at
one institution between 1991–5. The primary exposure,
absolute neutrophil count (ANC), was
summarized as mean ANC within a given week, using a five-level
stratification (reference > 1000/μl). ANC
stratum-specific rates of bacteraemia were calculated, by
organism type. Linear
trend tests were performed to assess dose-response relationship
between neutropenia and rates
of bacteraemia. The cohort included 1645 patients contributing
26785 patients-weeks and 191
episodes of bacteraemia. The unadjusted effect of neutropenia
was most evident for
bacteraemia due to E. coli (RR 3.4), Klebsiella
pneumoniae (RR 16·7), and P. aeruginosa
(RR 10.4). For bacteraemia due to any of these three
organisms (47 episodes), with reference ANC > 1000/μl,
relative rates were: 751–1000/μl,
1·12; 501–750/μl, 2.11;
251–500/μl, 13·58; 0–250/μl,
21·89.