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Randomized Controlled Trial
. 2008 Feb;43(1 Pt 1):327-39.
doi: 10.1111/j.1475-6773.2007.00745.x.

Addressing ceiling effects in health status measures: a comparison of techniques applied to measures for people with HIV disease

I-Chan Huang  1 , Constantine Frangakis, Mark J Atkinson, Richard J Willke, Walter L Leite, W Bruce Vogel, Albert W Wu
Affiliations
Randomized Controlled Trial

Addressing ceiling effects in health status measures: a comparison of techniques applied to measures for people with HIV disease

I-Chan Huang et al. Health Serv Res. 2008 Feb.

Abstract

Objectives: To compare different approaches to address ceiling effects when predicting EQ-5D index scores from the 10 subscales of the MOS-HIV Health Survey.

Study design: Data were collected from an HIV treatment trial. Statistical methods included ordinary least squares (OLS) regression, the censored least absolute deviations (CLAD) approach, a standard two-part model (TPM), a TPM with a log-transformed EQ-5D index, and a latent class model (LCM). Predictive accuracy was evaluated using percentage of absolute error (R(1)) and squared error (R(2)) predicted by statistical methods.

Findings: A TPM with a log-transformed EQ-5D index performed best on R(1); a LCM performed best on R(2). In contrast, the CLAD was worst. Performance of the OLS and a standard TPM were intermediate. Values for R(1) ranged from 0.33 (CLAD) to 0.42 (TPM-L); R(2) ranged from 0.37 (CLAD) to 0.53 (LCM).

Conclusions: The LCM and TPM with a log-transformed dependent variable are superior to other approaches in handling data with ceiling effects.

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Figures

Figure 1
Figure 1
Distribution of EQ-5D Index Scores.
See this image and copyright information in PMC

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