The Comorbidity Symptom Scale: A combined disease inventory and assessment of symptom severity

OBJECTIVES: To develop and evaluate a scale to quantify the presence and severity of symptoms arising from comorbid diseases in older people. DESIGN: A validation cohort study of hospital inpatients and outpatients aged 65 years and older. SETTING: A Hospital and community in Northeast England. PARTICIPANTS: Development of the Comorbidity Symptom Scale - Convenience sample of 50 hospital inpatients and outpatients aged 65 years and older. Evaluation of the Comorbidity Symptom Scale - Convenience sample of 183 patients aged 65 years and older either awaiting cataract surgery or attending a geriatric day hospital. MEASUREMENTS: For development of the Comorbidity Symptom Scale, 22 comorbid conditions were identified and incorporated into a questionnaire (the CmSS). Evaluation of the Comorbidity Symptom Scale - Assessments included the CmSS, activities of daily living, perceived health status, and anxiety and depression. RESULTS: A 23-item scale was developed. Reliability of the CmSS was demonstrated by a test-retest correlation coefficient for the total instrument score of r = 0.87 (P < .001). The CmSS scores correlated with assessments of activities of daily living, perceived health status, and anxiety and depression. CONCLUSIONS: The CmSS is a simple interviewer-administered tool for use in older people and provides an objective measure of the presence of comorbid disease and the patient's perception of severity of associated symptoms.