Performance status (PS) is a good prognostic factor in lung cancer and is used to assess chemotherapy appropriateness. Researchers studying chemotherapy use are often hindered by the unavailability of PS in automated data sources. To the authors' knowledge, no attempts have been made to estimate PS using claims-based measures. The current study explored the ability to estimate PS using routinely available measures.
A cohort of insured patients aged ≥50 years who were diagnosed with American Joint Committee on Cancer stage II through IV lung cancer between 2000 and 2007 was identified via a tumor registry (n = 552). PS was abstracted from medical records. Automated medical and pharmaceutical claims from the year preceding diagnosis were linked to tumor registry data. A logistic regression model was fit to estimate good versus poor PS in a random half of the sample. C statistics, sensitivity, specificity, and R2 were used to compare the predictive ability of models that included demographic factors, comorbidity measures, and claims-based utilization variables. Model fit was evaluated in the other half of the sample.
PS was available in 80% of medical records. The multivariable regression model predicted good PS with high sensitivity (0.88 or 0.94 depending on how good PS was defined), but moderate specificity (0.45 or 0.32) with a 0.50 prediction cutoff, and good sensitivity (0.64 or 0.83) and specificity (0.69 or 0.55) when the cutoff was 0.70. The goodness-of-fit c statistic was 0.76 or 0.78.
PS can be estimated, with some accuracy, using claims-based measures. Emphasis should be placed on documenting PS in medical records and tumor registries.