Assessing comorbidity in patients with Parkinson's disease.

The aim of this study was to assess the accuracy of an interview-based assessment of comorbidity, in patients with Parkinson's disease (PD). The Cumulative Illness Rating Scale-Geriatric (CIRS-G) was completed (1) in an interview with 31 PD patients and their caregivers, and (2) by reviewing the patient's medical charts from their general practitioners. Based on the interview, all patients had some comorbidity, 84% had one or more moderate comorbid diseases. The most frequently affected organ systems were "lower gastrointestinal" and "genitourinary". The mean +/- SD total score of the interview-based (chart-based) CIRS-G was 6.9 +/- 3.8 (7.6 +/- 3.5) with a mean of 4.3 +/- 1.9 (5.0 +/- 1.9) affected organ systems and a mean of 2.1 +/- 1.7 (2.3 +/- 1.6) organ systems with at least moderate comorbidity per patient. The agreement (intraclass correlation coefficients) between the interview-based and chart-based assessments for the six summary scores ranged from 0.69 to 0.81. The agreement for the 14 organ systems ranged from 0.13 to 1.00 (weighted kappa); 12 had a K(w) above 0.40 (moderate agreement). The comorbidity summary scores had a moderate correlation with age and disability. The interview-based assessment of the CIRS-G is easy to apply and is an accurate method to assess comorbidity in patients with PD.