Flexible Parametric Prognostic Risk Score Models For Short-Term Risk Of Aids On Patients Newly Initiated On Highly Active Antiretroviral Therapy (Haart) In Nyanza, Kenya

Abstract

About 22.9 million people living with HIV/AIDS reside in sub-Saharan Africa, many of

whom have progressed to AIDS over time. Kenya has high numbers of new infections;

a total of 104,000 in the general population with paediatrics at 13,000 and adults at

91,000. Risk scores constructed using prognostic factors may be valuable in the early

identication and intervention to patients at risk of progression to AIDS. There was

therefore a necessity to come up with robust risk models that use a limited number of

easily available factors. The main objective was to come up with a risk score utilizing

routine care data which can be easily applicable in a clinical setting to asses for risk

of AIDS among HIV infected patients. It was a prospective cohort study done using 2

year follow-up (initiated on Highly Active Antiretroviral Therapy (HAART)) between

1st of June, 2010 and 30th of May, 2011) data from 1454 HIV/AIDS on ART care and

treatment. Age, sex, marital status, CD4 cell count, haemoglobin level, BMI, prior TB

medication and whether or not patients were currently receiving any ART was modelled

to describe the short term risk of new AIDS event. Flexible parametric survival regression

analysis (Royston Parmar) was used instead of Cox-PH regression. Strong predictors of

progression were Body Mass Index, haemoglobin, World Health Organization staging and

Tuberculosis treatment prior to HAART initiation. The study was able to develop a two

group risk categorization based on the risk model developed. The discriminative ability

of the model was moderately strong (Harrell's c-index of 0.69). The rate of progression

to AIDS between the high and low risk groups was well dened. The rate of progression

was 0.38 and 0.93 per thousand person-years of followup for the low risk and high risk

groups respectively which was more than twofold risk of progression to AIDS among high

risk group, (HR= 2.47 95% CI: 1.66 - 3.69; p