Comparing the prevalence of multimorbidity using different operational definitions in primary care in Singapore based on a cross-sectional study using retrospective, large administrative data.

Fortin et al's list of conditions is most suitable for describing multimorbidity in the Singapore primary care setting. Prediabetes and 'physical disability' should be added to Fortin et al's list to augment its comprehensiveness. We propose a similar study methodology be performed in other countries to identify the most suitable operational definition in their own context.