In this large cohort of unselected HIV-infected patients who were PI naive at the initiation of cART and followed for more than 7 years, a high frequency of non-AIDS events was observed. Non-AIDS events appeared as the most frequent clinical events, respectively, 3-fold and 4-fold more frequent than cART-related and AIDS-defining events. Among these non-AIDS events, it was noteworthy that occurrence of a first non-AIDS-defining bacterial infection was strongly associated with an uncontrolled viral load.
The use of cART has completely changed the natural history of HIV infection and the spectrum of morbidity and mortality in the HIV-infected population.2 From an acute-subacute disease almost invariably progressing to AIDS and death with occurrence of highly lethal opportunistic infections, HIV infection became a controllable chronic infection with a life expectancy approximating that of the general population when the CD4 cell count is maintained at >500 cells per milliliter.9 Thus, HIV-infected patients live older on cART, and these patients are now exposed to development of non-AIDS-defining illnesses that may be the consequence of multiple factors, related or not related (age and comorbidities) to HIV infection.5,10
In our study, age >60 years was an independent risk factor for developing non-AIDS events and particularly non-AIDS cancers. Aging is associated with immune dysfunction also called immunosenescence (decline of both innate and adaptive immune responses with age) that may, besides other risk factors, explain the increasing risk of infection and cancer with age.11 The recent Strategies for Management of Antiretroviral Therapy (SMART) study well established the increase of age as a risk factor for non-AIDS cancers in the HIV-infected population.12
The level of CD4 cell count is known as a strong prognostic factor for the occurrence of opportunistic AIDS-defining diseases in the HIV population.13 In our study, a CD4 cell count <100 cells per milliliter was also an independent factor for the occurrence of a first non-AIDS event, particularly bacterial infections that were the most frequent non-AIDS events. In the pre-cART era, bacterial pneumonia was already known as a frequent HIV-associated respiratory infection in individuals with HIV and recurrent pneumonia, often associated with a low CD4 cell count, is classified as an AIDS-defining event. In the same way, there was a trend toward an association between the level of CD4 cell count <500 cells per milliliter and the occurrence of a first event in relation with a non-AIDS cancer that was the second cause of non-AIDS events in our study. Non-AIDS-defining malignancies became a major cause of death among HIV-infected patients in industrialized nations in the cART era, and some non-AIDS-defining malignancies have been found with a higher frequency among HIV-infected patients as compared with the general population.14,15 The relationship between the level of CD4 cell count and the incidence of non-AIDS cancers is unclear and debated and may be different when considering particular types of cancer.14-16 Many data now support the role of immune suppression in the development of non-AIDS-defining malignancies.12,17 Moreover, in a recent study, the duration of exposure to a low CD4 cell count was associated with a higher risk of both AIDS-defining and non-AIDS-defining cancers.18 Finally, Lewden et al4 recently showed that the mortality of patients with a patent CD4 restoration (CD4+ cell count ≥500 cells/mL) reached the level of the general population 6 years and more after the initiation of cART. In this study, in patients who spent time with a CD4+ cell count between 350 and 499 cells per milliliter, mortality remained higher than in the general population, indicating that intermediate level of CD4 may provide immunological conditions for developing fatal clinical events. Our study and the data from a recent study performed in the Aquitaine cohort suggest that the survival advantage conferred by complete restoration of CD4+ cell count >500 per cubic millimeter may be related to protection against the development of non-AIDS-defining cancers.18
Immunosuppression not directly related to the level of the CD4 cell count may also be observed in HIV-infected patients. Unlike classical opportunistic infections, the risk of bacterial infections (especially bacterial pneumonia) depends to a lesser degree on the level of CD4+ cell count as bacterial infections can occur within all CD4+ cell strata.19 Emerging data from both humans and monkeys suggest that the recovery of CD4+ T cells in peripheral blood during the treatment of HIV infection could be associated with a persistent immunosuppressive status.19 First, during chronic HIV infection, cART induces the increase of peripheral CD4+ cells but may not completely restore the CD4+ T-cell repertoire and may fail to limit the destruction of the CD4+ memory compartment at the mucosal surface. This may lead to a substantial reduction in the CD4 function and immunologic resources, particularly at tissue-environment interfaces (such as the airway and digestive tract), that may facilitate the occurrence of bacterial infections (such as pneumonia) or non-AIDS cancers (such as lung and digestive cancers).19
Our observation that uncontrolled HIV replication per se may be an independent factor associated with the occurrence of non-AIDS events and particularly bacterial infections has not been previously reported. Indeed, indirect arguments were provided by studies based on a CD4+ count-guided interruption of antiretroviral treatment, as patients interrupting cART were at a higher risk for developing non-AIDS events than patients with continuous cART therapy whatever their CD4+ cell count.7,8,12 Uncontrolled HIV replication per se may induce a state of immunosuppression independent of the CD4 cell count but this has not been clearly demonstrated. In the SMART study, it was noteworthy that authors also recorded a higher risk for developing other complications, such as cardiovascular diseases, raising questions about the contribution of uncontrolled HIV replication to short-term vascular risk.8 The potential underlying mechanism of such an association remains to be determined, but the inflammatory response of the host against the viral replication leading to the endothelial dysfunction and hypercoagulable status is a hypothesis.20
Occurrence of non-AIDS cancers in the HIV population may be due to a particular exposition to carcinogens. Smoking is a well-known carcinogen (and also contribute to occurrence of bacterial pneumonia and ischemic cardiovascular events), and HIV-infected patients typically use tobacco more heavily than the general population.21 SMART study well established the increase of smoking as risk factors for non-AIDS cancers in the HIV-infected population.12 In our study, it is noteworthy that we recorded a high number of digestive tumors, such as colorectal adenocarcinoma, that are less smoking related than other cancers such as lung and head and neck cancers. This particularity and also the lack of power due to the low number of non-AIDS cancer-related events may explain the absence of association between smoking and cancers in our study. Our population may be also exposed to other carcinogens. First, HIV itself may have an oncogenic role, as the tat gene product can modulate the expression of certain proto-oncogenes in tumor cell lines in vitro.22 Finally, it is not excluded that cART may have a carcinogenic effect during a long-term exposition.23
Neuropsychiatric disorders (that may preexist before the HIV infection) represent almost 15% of all non-AIDS events in our study, and depression was the most common one. As it has been demonstrated that depression was independently associated with nonadherence, association between neuropsychiatric disorder and uncontrolled viral load may be partly due to nonadherence.24 However, it is not excluded that uncontrolled HIV replication may be partly responsible for neuropsychiatric disorders as HIV could be responsible for dementia and encephalopathy. Moreover, HCV-related cognitive impairment has been described (and supported by molecular virological studies of postmortem brain tissue), and HIV and HCV coinfection may have a synergic effect on the central nervous system function.25 The occurrence of neuropsychiatric disorders could also be related with characteristics of the population as they are particularly frequent in injection drug users.
Finally, we observed few complication of cirrhosis in this cohort, whereas 22.9% and 4.8% of our patients were coinfected with HCV and hepatitis B virus, respectively. This may be explained by the positive impact of cART on the natural course of both chronic hepatitis B and C. The relation we observed between HCV coinfection and morbidity may be more in relation with risky behaviors or socioeconomic conditions of this population.26
Our study has some limitations. First, our results were obtained from an observational study, with all its potential selection biases, and need to be confirmed by further and independent investigations. Second, non-AIDS events are very heterogeneous as they belong to very different classes of diseases such as bacterial infections, malignancies, or psychiatric illnesses, which may have various etiologies depending on the HIV-positive population, its way of living (including alcohol consumption that may be a confounding factor), and/or directly or indirectly on the HIV infection itself. Moreover, we did not use a control HIV-negative group with similar age, sex, and hepatitis C coinfection, which could allow to verify if the incidence of these events was more frequent than what could be expected. Finally, some of non-AIDS events such as cardiovascular events or liver diseases may be due, at least in part, to antiretroviral drugs as a causal relationship with therapy is suspected but has not been firmly established. On the other hand, the prolonged follow-up and the exhaustive and prospective recording, along with the scoring and categorization of all severe clinical events (ie, not only AIDS-defining and solely drug-related events), by an Events Validation Committee of clinician experts who assessed collegially each event are great strengths of our study. We were thus able to describe a representative spectrum of severe clinical events that occur in cART-treated HIV-infected patients within the context of a standard clinical practice in a developed European country.
In conclusion, non-AIDS events have become the most frequent severe clinical events in HIV-infected patients on long-term antiretroviral therapy. In our study, an age >60 years, a low CD4 cell count, and a moderate level of HIV replication were independently associated with the occurrence of non-AIDS events during the prolonged follow-up. Our results give further arguments against interruption of cART and underline the need to avoid virological rebound (also during salvage therapy), particularly in older patients and/or those with a low CD4 cell count. Optimization and permanent continuation of long-term antiretroviral therapy in HIV-infected patients is the best strategy to prevent or reduce the occurrence of non-AIDS severe morbidity.
APROCO-COPILOTE ANRS CO8 study group-Scientific Committee: Steering Committee: Principal Investigators: C. Leport and F. Raffi. Methodology: G. Chêne and R. Salamon. Social Sciences: J.-P. Moatti, J. Pierret, and B. Spire. Virology: F. Brun-Vézinet, H. Fleury, and B. Masquelier. Pharmacology: G. Peytavin and R. Garraffo. Other members: D. Costagliola, P. Dellamonica, C. Katlama, L. Meyer, D. Salmon, and A. Sobel. Events Validation Committee: L. Cuzin, M. Dupon, X. Duval, V. Le Moing, B. Marchou, T. May, P. Morlat, C. Rabaud, and A. Waldner-Combernoux. Project Coordination: F. Collin-Filleul. ANRS Representatives: Nadine Job-Spira and Marcia Trumeau. Observers: C. Perronne. Clinical Research Group: V. Le Moing and C. Lewden. Data Monitoring and Statistical Analysis: J. Biemar, S. Boucherit, A. D. Bouhnik, C. Brunet-François, M. P. Carrieri, F. Couturier, J. L. Ecobichon, V. Guiyedi, P. Kurkdji, S. Martiren, M. Préau, C. Protopopescu, C. Roy, J. Surzyn, A. Taieb, V. Villes, and C. Wallet. Promotion: Agence Nationale de Recherches sur le Sida et les hépatites virales (ANRS, Action Coordonnée n°7). Other Financial Supports: Collège des Universitaires de Maladies Infectieuses et Tropicales (CMIT ex APPIT) and Sidaction Ensemble contre le Sida, et laboratoires: Abbott, Boehringer-Ingelheim, Bristol-Myers Squibb, Gilead, GlaxoSmithKline, and Roche. Clinical Centers (coordinators): Amiens (Pr J. L. Schmit), Angers (Dr J. M. Chennebault), Belfort (Dr J. P. Faller), Besançon (Pr J. L. Dupond, Dr J. M. Estavoyer, and Dr Drobachef), Bobigny (Pr O. Bouchaud), Bordeaux (Pr M. Dupon, Pr Longy-Boursier, Pr P. Morlat, and Pr J. M. Ragnaud), Bourg-en-Bresse (Dr P. Granier), Brest (Pr M. Garré), Caen (Pr R. Verdon), Compiègne (Dr D. Merrien), Corbeil-Essonnes (Dr A. Devidas), Créteil (Pr A. Sobel), Dijon (Pr H. Portier), Garches (Pr C. Perronne), Lagny (Dr P. Lagarde), Libourne (Dr J. Ceccaldi), Lyon (Pr D. Peyramond), Meaux (Dr C. Allard), Montpellier (Pr J. Reynes), Nancy (Pr T. May), Nantes (Pr F. Raffi), Nice (Pr J. G. Fuzibet and Pr P. Dellamonica), Orléans (Dr P. Arsac), Paris (Pr E. Bouvet, Pr F. Bricaire, Pr P. Bergmann, Pr J. Cabane, Dr J. Monsonego, Pr P. M. Girard, Pr L. Guillevin, Pr S. Herson, Pr C. Leport, Pr M. C. Meyohas, Pr J. M. Molina, Pr G. Pialoux, and Pr D. Salmon), Poitiers (Pr B. Becq-Giraudon), Reims (Pr R. Jaussaud), Rennes (Pr C. Michelet), Saint-Etienne (Pr F. Lucht), Saint-Mandé (Pr T. Debord), Strasbourg (Pr J. M. Lang), Toulon (Dr J. P. De Jaureguiberry), Toulouse (Pr B. Marchou), and Tours (Pr J. M. Besnier).
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Keywords:© 2009 Lippincott Williams & Wilkins, Inc.
cART; HIV; morbidity; non-AIDS events; viral load