Background: It is unclear whether lack of immunological response despite viral suppression and relatively preserved CD4+ T-cell count is associated with increased risk of AIDS or severe non-AIDS events.
Methods: Patients initiating first combination antiretroviral therapy (cART) were studied from first viral load 80 copies/ml or less up to AIDS, serious non-AIDS events (malignancies, severe infections, acute kidney injury, cardiovascular events, liver decompensation) or death. Follow-up was right censored if viral load was more than 500. Immunological nonresponse (INR) was defined as current CD4+ cell count less than 120% pre-cART. A Poisson regression analysis was used to investigate the association between INR and the outcome.
Results: Three thousand, three hundred and seventy-eight patients were followed for a median of 32 months (interquartile range: 15–67). Two hundred and twenty-two events (32 deaths, 39 AIDS-defining events, 48 malignancies, 32 severe infections, 47 acute kidney injuries, 12 cardiovascular events, 12 other nonfatal events) were observed. The rate of clinical events among INR and immunological responders was 4.41 [95% confidence interval (CI) 3.38–5.74] and 1.84 (95% CI 1.58–2.15) per 100 person years of follow-up, respectively, accounting for a crude rate ratio of 2.39 (95% CI 1.77–3.25; P < 0.001). INR remained an independent predictor of clinical progression after adjusting for baseline characteristics, including pre-cART CD4+ cell count (adjusted rate ratio 2.93; 95% CI 2.06–4.16, P < 0.001) or current CD4+ cell count (adjusted rate ratio 1.94; 95% CI 1.39–2.72, P < 0.001). The association did not vary by pre-cART CD4+ cell counts (P for interaction = 0.93)
Conclusion: INR are at higher risk of severe clinical events than responders. The association was consistent across different CD4+ cell counts at cART initiation and was only partially explained by current CD4+ cell count. INR could be a marker of immune system malfunctioning, not completely captured by absolute CD4+ cell count.
aClinic of Infectious Diseases, ‘San Gerardo de’ Tintori’ Hospital, Monza, Italy
bDepartment of Infection and Population Health, Division of Population Health, Hampstead Campus, University College London, UK
cIstituto Nazionale per le Malattie Infettive, Rome
dClinic of Infectious Diseases, ‘San Paolo’ Hospital, University of Milan
eClinic of Infectious Diseases, Hospital of Macerata
fClinic of Infectious Diseases, ‘Spirito Santo’ Hospital, Pescara
gClinic of Infectious Diseases, ‘Luigi Sacco’ Hospital, University of Milan, Italy.
Correspondence to Giuseppe Lapadula, MD, PhD, Clinic of Infectious Diseases, ‘San Gerardo de’ Tintori’ Hospital, Monza, Italy. E-mail: email@example.com
Received 14 August, 2012
Revised 12 November, 2012
Accepted 16 November, 2012
This work has been presented in part at the 19th Conference on Retroviruses and Opportunistic Infections, Seattle, March 5th–8th 2012. Abstract 641.
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