Assessing HIV lipodystrophy syndrome : a comparison of different methods to an objective case definition

Abstract

Background: Morphological changes of Human Immunodeficiency Virus lipodystrophy syndrome (HIV LDS) are said to be the new face of HIV / Acquired Immune Deficiency Syndrome (AIDS) which may negatively influence the adherence to Highly Active Antiretroviral Therapy (HAART). Methods of assessing HIV LDS vary among researchers and practitioners who make it difficult to compare incidence and prevalence figures among clinics in South Africa. Instruments available in other countries to assess HIV LDS are costly and time consuming for the clinical setup. A standard, objective and practical instrument is needed for the South African clinical setup to address this problem. Objectives: The primary objective of the study was to assess the agreement between methods routinely used to classify HIV LDS in the clinical setup (i.e. National Cholesterol Education Programme [NCEP] criteria, subjective self-reporting and routine anthropometry) to a published, objective case definition using diagnostic testing. The secondary objective was to develop and cross-validate a classification instrument for HIV LDS utilising parameters from the studied test methods. Design and sample: The study was a cross-sectional, analytical and non-experimental analysis of 1421 HIV positive adult patients (69% female) enrolled on HAART. Of the 283 subjects who met the inclusion criteria, 253 consented to participate. Purposeful sampling was performed dividing the study population into a case (n=79) - and control (n=73) group according to a screening process. The dichotomous outcome (HIV LDS (+) or – Ө) of the tests – and reference method was statistically analysed by means of diagnostic testing. The new classification instrument was developed using logistic regression on all the variables and validated with a cross-validation technique. Setting: Outpatient clinic at Kalafong Hospital, Gauteng Province, South Africa. Results: Primary objective: The diagnostic properties (sensitivity, specificity, Kappa coefficient and p-value for McNemar’s test respectively) of the test methods were as follows: NCEP criteria: (45%, 83%, 0.29 and 0.54); subjective self-reporting (74%, 59%, 0.26 and 0.00); Kotler anthropometry (71%, 52%, 0.18 and 0.00); routine anthropometry (62%, 54%, 0.12 and 0.00); and Dong&Hendricks anthropometry: (10%, 88%, 0.00 and 0.00). Secondary objective: A new, simple classification instrument (with limited blood samples) had the following diagnostic properties: (sensitivity 81% [71% validated], specificity 79% [75% validated], Kappa 0.54 [0.41 validated], McNemar’s test of symmetry p=0.00, and the area under the receiver operating curve [AUC] was 0.88). A classification instrument without blood samples had a sensitivity of 69%, specificity of 67%, Kappa = 0.310, McNemar’s p= 0.00 and AUC= 0.75). Conclusion: In a resource limited setting the NCEP criteria appears to be the “best” among the methods tested for identifying HIV LDS. Two newly developed instruments showed even better diagnostic properties. Use of these might lead to an accurate, consistent detection of HIV LDS in the typical South African setting. However, practical implications to the individual and the health care system still need to be investigated further. The results can also be used in longitudinal studies.