Pneumonia in HIV-infected patients: a case-control survey of factors involved in risk and prevention.

OBJECTIVE

To assess the factors that increase or decrease the risk of pneumonia with particular attention to immunization with pneumococcal and influenza vaccines in a group of HIV-infected persons.

DESIGN

A retrospective, case-control study based on information entered into a standard database and the medical record.

SETTING

Patients attending a referral clinic specializing in AIDS/HIV care at a public hospital.

PATIENTS: Among over 2000 subjects entered into a database in 8 years, 127 incidents of pneumonia were identified from the record. These cases were matched with 127 CD4 cell count matched, concurrent controls.

INTERVENTIONS: None.

MAIN OUTCOME MEASURE: The principal hypothesis was that chart review would find a decreased frequency of pneumococcal immunization in the pneumonia cases compared with matched controls.

RESULTS

Pneumococcal immunization was associated with a reduction of the risk of pneumonia by nearly 70%. The effect was seen even when immunization was given with a CD4 cell count of less than 100/mm3. Injection drug users and African-Americans had a twofold increased risk of pneumonia.

CONCLUSION

The study provides data to support the current recommendation for pneumococcal immunization of all HIV-infected persons. Although this conclusion could lead to renewed enthusiasm for increasing pneumococcal immunization rates in HIV-infected persons, it must be recognized that the study is observational and ascertainment bias cannot be excluded.