Withholding primary PcP prophylaxis in virologically suppressed HIV patients: An emulation of a pragmatic trial in COHERE.

BACKGROUND

Using data from the COHERE collaboration, we investigated whether primary prophylaxis for Pneumocystis Pneumonia (PcP) might be withheld in all patients on antiretroviral therapy with suppressed plasma HIV RNA (≤ 400c/mL) irrespective of CD4 count.

METHODS

We implemented an established causal inference approach whereby observational data is used to emulate a randomised trial. Patients taking PcP prophylaxis were eligible for the emulated trial if their CD4 count was ≤ 200 cells/µL in line with existing recommendations. We compared the following two strategies for stopping prophylaxis: i.) when CD4 count was above 200 cells/µL for more than 3 months, or ii.) when the patient was virologically suppressed (two consecutive HIV RNA ≤ 400c/mL). Patients were artificially censored if they did not comply with these stopping rules. We estimated the risk of primary PcP in patients on ART, using the hazard ratio to compare the stopping strategies by fitting a pooled logistic model, including inverse probability weights to adjust for the selection bias introduced by the artificial censoring.

RESULTS

4'813 patients (10'324 person years) complied with eligibility conditions for the emulated trial. With primary PcP diagnosis as endpoint, the adjusted hazard ratio (aHR) indicated a slightly lower, but not statistically significant, different risk for the strategy based on viral suppression alone compared to the existing guidelines (aHR 0.8 with 95% CI [0.6, 1.1], p = 0.2).

CONCLUSIONS

The study suggests that primary PcP prophylaxis might be safely withheld in confirmed ART-virologically suppressed patients, regardless of their CD4 count.