The object of this article was to systematically review available methods to measure comorbidity and to assess their validity and reliability. A search was made in Medline and Embase, with the keywords comorbidity and multi-morbidity, to identify articles in which a method to measure comorbidity was described. The references of these articles were also checked, and using a standardized checklist the relevant data were extracted from these articles. An assessment was made of the content, concurrent, predictive and construct validity, and the reliability. Thirteen different methods to measure comorbidity were identified: one disease count and 12 indexes. Data on content and predictive validity were available for all measures, while data on construct validity were available for nine methods, data on concurrent validity, and interrater reliability for eight methods, and data on intrarater reliability for three methods. The Charlson Index is the most extensively studied comorbidity index for predicting mortality. The Cumulative Illness Rating Scale (CIRS) addresses all relevant body systems without using specific diagnoses. The Index of Coexisting Disease (ICED) has a two-dimensional structure, measuring disease severity and disability, which can be useful when mortality and disability are the outcomes of interest. The Kaplan Index was specifically developed for use in diabetes research. The Charlson Index, the CIRS, the ICED and the Kaplan Index are valid and reliable methods to measure comorbidity that can be used in clinical research. For the other indexes, insufficient data on the clinimetric properties are available.

No abstract

The object of this article was to systematically review available methods to measure comorbidity and to assess their validity and reliability. A search was made in Medline and Embase, with the keywords comorbidity and multi-morbidity, to identify articles in which a method to measure comorbidity was described. The references of these articles were also checked, and using a standardized checklist the relevant data were extracted from these articles. An assessment was made of the content, concurrent, predictive and construct validity, and the reliability. Thirteen different methods to measure comorbidity were identified: one disease count and 12 indexes. Data on content and predictive validity were available for all measures, while data on construct validity were available for nine methods, data on concurrent validity, and interrater reliability for eight methods, and data on intrarater reliability for three methods. The Charlson Index is the most extensively studied comorbidity index for predicting mortality. The Cumulative Illness Rating Scale (CIRS) addresses all relevant body systems without using specific diagnoses. The Index of Coexisting Disease (ICED) has a two-dimensional structure, measuring disease severity and disability, which can be useful when mortality and disability are the outcomes of interest. The Kaplan Index was specifically developed for use in diabetes research. The Charlson Index, the CIRS, the ICED and the Kaplan Index are valid and reliable methods to measure comorbidity that can be used in clinical research. For the other indexes, insufficient data on the clinimetric properties are available.

This is the first study to investigate the recovery of arm function after stroke over a period of 4 years. It is encouraging to note that even after 16 weeks improvement still occurred in some patients. However, considerable long-term loss of arm function, associated disability and perceived problems were found. There is an obvious need to develop effective treatment methods for hemiplegic arm function.

SummaryResearch articles on the prognosis of stroke patients were analysed to identify studies that met sound methodological principles of prognostic research as well as to identify variables capable of predicting functional outcome (ADL) after stroke. Data sources comprised a computer-aided search of published prognostic studies and references to literature used in prognostic studies. Seventy-eight studies were tested for adherence to the following key methodological criteria: reliability and validity of measurement instruments used to assess dependent and independent variables; inclusion of an inception cohort; adequate and uniform end-point of observation; control for drop-outs during period of observation; statistical testing of presumed relationship between dependent and independent variables; sufficient sample size in relation to number of determinants; control for multicollinearity; specification of patient characteristics (i.e. age, type, recurrent stroke and localization of stroke); description of interfering treatment effects during the period of observation; and crossvalidation of the prediction model in a second independent group of patients.Only three studies satisfied nine out of 11 criteria and ten studies eight criteria for the determination of valid prognostic research. The results of these studies indicate that the following variables are valid predictors for functional recovery after stroke: age; previous stroke; urinary continence; consciousness at onset; disorientation in time and place; severity of paralysis; sitting balance; admission ADL score; level of social support and metabolic rate of glucose outside the infarct area in hypertensive patients. This study supports the general opinion that not only are differences in objectives and heterogeneity in stroke patients responsible for the lack of accuracy in predicting functional outcome, but also the methodological flaws in published prognostic research.