What is the prevalence of neurocognitive impairment in HIV-infected patients in the United Kingdom?
Since the introduction of highly active antiretroviral therapy (HAART) there has been a dramatic decline in HIV related morbidity and mortality including incident cases of HIV-associated dementia (HAD). Recent reports from observational cohorts around the world have shown a high prevalence of HIV-associated neurocognitive disorders (HAND). There is however, at present, no such data in the UK. Cases of asymptomatic neurocognitive impairment (ANI) have also been reported in patients who are stable on HAART. Different antiretroviral (ARV) regimes have varying CNS penetration effectiveness (CPE) and if this is shown to influence the prevalence of HAND, it could in turn influence ARV initiation and the switching of regimes.
The trial is a multi-centre, epidemiological cohort study investigating the prevalence of neurocognitive impairment amongst patients living with HIV infection attending outpatient clinics at two London hospitals.
Each patient has undertaken a battery of tests including a computerised neurocognitive testing (CogState; CogState Ltd, Melbourne Australia), a Hospital Anxiety and Depression Score and three screening questions relating to signs of symptomatic cognition. Baseline demographical data and clinical history (e.g. co-morbidities, medications, alcohol and drug use) has been obtained via patient interview and medical notes review.
793 patients were recruited and statistical analysis of the results is currently in process. Our primary endpoint is to assess the prevalence of neurocognitive impairment (NCI) in this cohort of HIV-infected subjects. NCI will be defined as >1 standard deviation below the mean in two or more domains, when compared routine age-matched individuals. There are several domains within the CogState battery ranging from executive function to short term memory. Our secondary endpoints are to assess the demographic variables that relate to the presence of NCI and the relationship that differing antiretroviral regimes have on the prevalence and severity of NCI in this cohort, using the Central Nervous System Penetration Effectiveness Ranking Score (CPE).
If a correlation between a high CPE and reduced incidence of NCI is found, this could influence clinicians’ choice of antiretroviral regime. A comparison with cruder tests such as the Hospital Anxiety and Depression Score will be useful as it will allow us to consider whether such tests can help in the stratification of NCI. Additionally, those found to have cognitive impairment or an undiagnosed psychiatric comorbidity will be referred by the physician in charge of their care within the clinics for further investigation and treatment as clinically indicated.