The Swiss StopCox Study: Is It Safe to Discontinue PCP Prophylaxis in Patients with Detectable Viremia, Low Nadir CD4 Count or T. gondii Seropositivity?

H. FURRER*¹, M. OPRAVIL², M. ROSSI¹, E. BERNASCONI³, A. TELENTI⁴, H. BUCHER⁵, B. HIRSCHEL⁶, P. VERNAZZA⁷, M. RICKENBACH⁸, M. FLEPP², and M. EGGER⁹ for the Swiss HIV Cohort Study. Swiss HIV Cohort Ctrs. of ¹Bern, ²Zurich, ³Lugano, ⁴Lausanne, ⁵Basel, ⁶Geneva, ⁷St. Gall, ⁸SHCS Data Ctr., Switzerland; and ⁹Univ. Bristol UK

Background: As shown previously, discontinuation of primary PCP prophylaxis is safe in patients with sustained increase of CD4 counts (NEJM 1999;340:1301). To further address the safety of this strategy in patients with low nadir CD4 counts, detectable viremia or those at risk of developping toxoplasma encephalitis (TE) we present the follow up analysis of the Swiss HIV Cohort Study.
Design: Prospective multicenter study of safety of discontinuation of primary PCP prophylaxis in patients with sustained (>12wk) increase of CD4 count to at least 200/ml and 14%.
Patients: 381 (31% female, median age 38y) patients were enrolled. Med. nadir CD4 count was 105/ml  (IQR 94). At enrollment median CD4 count was 327/ml  (IQR 132) and med. HIV RNA was 2 log₁₀ c/ml (IQR 0.88). 176 (47%)  were seropositive for T.gondii IgG and thus at risk for TE. Med. follow-up was 490d (IQR 353d) and total follow-up 473 py.
Results: One patient was diagnosed with PCP (CD4 at diagnosis 530/ml, HIV RNA <50c/ml). He presented with chronic cough without dyspnea or fever, Xray of thorax and serum LDH level  were normal. P.carinii was found in sputum.
Incidence of PCP/TE:
PCP:
-total: N=381; Follow-up 473 py; 1 event; Incidence  0.2 /100py (upper 95% conf.level 1.2).
-nadir CD4<100:  N=176; Follow-up 205py; 0 events; Incidence  0/100py (upper 95% conf.level 1.5).
-HIV RNA>2log₁₀ at enrollemnt: N=157; Follow-up 207py; 0 events, Incidence 0/100py (upper 95% conf.level 1.4).
TE in patients seropositive for T.gondii IgG:N=176; Follow-up 217py; 0 events; Incidence 0/100py (upper 95% conf.level 1.4).
Conclusion: Regardless of nadir CD4 count, detectable HIV RNA and seropositivity for T.gondii IgG, discontinuation of primary PCP prophylaxis is safe in patients on HAART with a sustained increase of  CD4 counts to at least 200/ml and 14%.

Key Words: Pneumocystis carinii, Prophylaxis, Toxoplasmosis

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