POTENTIAL FOR BIAS IN STUDIES OF THE INFLUENCE OF HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION ON THE RECOGNITION, INCIDENCE, CLINICAL COURSE, AND MICROBIOLOGY OF PELVIC INFLAMMATORY DISEASE

As the human immunodeficiency virus (HIV) epidemic affects more women, clinicians are increasingly observing pelvic inflammatory disease (PI D) in HIV-infected women. The extent to which PID is a factor in the r ecognition of HIV or HIV is a factor in the recognition of PID is unkn own. Even less is known about how HIV infection influences the develop ment, clinical course, and microbiology of PID. The paucity of existin g data largely results from difficulties in designing studies that are free of bias. Several biases may distort studies of the effect of HIV on the recognition, incidence, clinical presentation and course, and microbiology of PID. Selection bias, diagnostic bias, and confounding bias are the most likely causes of invalid conclusions in studies of t he influence of HIV infection on these aspects of PID, for three major reasons: Factors that determine patients' health care seeking behavio r may be related to HIV status; the diagnosis of PID tends to be impre cise; and extraneous factors that cause or prevent PID may be distribu ted differently in HIV-infected and HIV-uninfected women. Appropriate study design and analytic techniques can eliminate, reduce, or estimat e the magnitude and direction of these biases, thereby yielding more v alid conclusions. To interpret properly existing and future studies of the influence of HIV infection on PID, clinicians must consider sever al biases that may distort results.