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Abstract:
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The KDQOL-36 is a short form version of the Kidney Disease Quality of Life Instrument, including 12 items comprising the SF-12 Physical and Mental Component Summary scales (PCS and MCS). We administered the survey to 9,071 Medicare beneficiaries with end-stage renal disease participating in a quality improvement demonstration program. At least one SF-12 item was missing for 21% of respondents, resulting in missing PCS and MCS scores. We will compare three data imputation approaches: item substitution (substituting a correlated item from the same respondent); multiple imputation; and mean imputation, repeated for a maximum number of missing items ranging from 1 to 12. We will simulate missing values from surveys with complete SF-12 data, replicating missing data patterns observed in the original data. We will impute missing values, and compare true MCS and PCS scores against those calculated from imputed data. Evaluation criteria will include bias, precision measured by mean square error, and sample size recovered. We will evaluate the pros and cons of each approach, considering ease of implementation and replicability.
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