A research team has developed a simplified clinical scoring system to assess the severity of HIV disease in children. The Simple Pediatric AIDS Severity Score does not require CD4 percentage values or viral load measurements, and is intended for use in resource-limited settings where these more expensive tests may not be available.
In developed countries, decisions about when to start antiretroviral treatment are based on (in adults) CD4 cell counts, HIV viral load measurements, and clinical symptoms, and (in children) CD4% values, HIV viral load, and clinical symptoms. CD4 and viral load assays are expensive enough that they are often unavailable in resource-poor countries in Africa and the developing world, and simpler assays and clinical measures have been suggested as alternatives.
In a paper in the December 15th issue of the Journal of Acquired Immune Deficiency Syndromes,a group of researchers from the Pediatric AIDS Clinical Trials Group (PACTG) has assessed a simplified “Pediatric AIDS Severity Score” (PASS), which uses only simpler, less expensive clinical measurements and assays. The Simple PASS model was tested in 952 HIV-positive children and found to be very strongly able to predict the severity of their illness and risk of mortality.
Pediatric AIDS Clinical Trials Group (PACTG) study 219, a prospective cohort study, enrolled 1178 HIV-positive children in the US between 1993 and 1996 (the “study population”). A wide range of measurements were collected from these children at regular ongoing visits, and used to construct a Pediatric AIDS Severity Score (PASS). The PASS was validated in a separate group of 952 children from other PACTG trials, followed between 1991 and 1997 (the “validation population”). Children in both populations ranged up to 14 years old (most were under seven), and were mostly non-white. Boys and girls were represented about equally.
The following measures were analysed as to how well they predicted the length of life remaining: weight by percentile, World Health Organization (WHO) scale (1 = asymptomatic/mild, 2 = moderate, 3 = severe/AIDS-defining conditions), mean symptom score from a 20-point scale for pediatric use, general health assessment score on a 1-10 scale, total lymphocyte count, white blood cell count, packed-cell volume, albumin, CDC clinical category (N/A = asymptomatic/mild, B = moderate, C = severe), CD4 percentage, and history of antiretroviral use. Several statistical analyses were used to determine the predictive power of these measurements.
Analysis showed that a model (the Simple PASS model) based on weight percentile, WHO stage, symptoms score, general health rating, total lymphocyte count, packed-cell volume, and albumin had a good ability to predict the risk of death. The report states that “an easy and practical scoring system combining all of these measures was developed (Simple PASS) and found to be highly predictive of mortality…although CD4 percentage did improve the predictive power… the Simple PASS model was able to distinguish those children with a poorer prognosis”.
The researchers believe that the Simple PASS model “will hold its predictive ability in … resource-limited countries”, however, it will need to be adapted to take into account (e.g.) the poor nutritional status and different range of infectious diseases that children are exposed to in these areas.
Patel K et al.