Classification of HIV disease in children - Towards pragmatism?
HIV infection is a multisystem disease characterised by progressive immunodeficiency and increasing susceptibility to common and opportunistic pathogens. Progressive disease is characterised by reversible and then permanent end-organ dysfunction due to HIV itself or co-pathogens, and also an increased risk of malignancy. The hallmark of immunodeficiency is CD4+ lymphocyte depletion, although other elements of the immune system are also deranged. Children with HIV are classified according to clinical and immunological criteria. Both systems are useful for individual patient management, and together are more useful than either parameter individually. Classification into mutually exclusive categories allows standardisation of this complex multisystem disease process, facilitating case management and informing the clinician of both the extent of clinical progression and prognosis. Because of the varied prevalence of pathogens in different geographical areas, disease manifestations may differ. Some pathogens, such as Pneumocystis jiroveci and cytomegalovirus (CMV), will cause the same disease manifestations in any location. Others, such as Mycobacterium tuberculosis, are more prevalent in sub-Saharan Africa than elsewhere. A classification system should take cognisance of this variability. Decisions to initiate antiretroviral therapy (ART) or to change therapy because of regimen failure are based on an understanding of disease progression. Lastly, the classification system allows for surveillance, facilitating planning by ministries of health for adequate resources and equitable access to care.