Charlson index and variation: 38 studies
Charlson et al developed this score for evaluating prognosis based on age and weighting for specific comorbid conditions. The validity of the Charlson index has been studies more extensively than other measures, particularly in hospital and specialist setting. Although it was developed and validated in hospitalized patients, it has since been adapted and validated in primary care and community populations. There are several variations of the Charlson index, but studies comparing these variations suggest they produce similar results. The majority of studies using the Charlson index described the effect of multi morbidity on health outcomes, particularly mortality.