Development of a new comorbidity index for adults with cerebral palsy and comparative assessment with common comorbidity indices

Abstract

Aim To develop a new comorbidity index for adults with cerebral palsy (CP), the Whitney Comorbidity Index (WCI), which includes relevant comorbidities for this population and better predicts mortality than the Charlson Comorbidity Index (CCI) and Elixhauser Comorbidity Index (ECI). Method Data from the Optum Clinformatics Data Mart was used for this retrospective cohort study. Diagnosis codes were used to identify adults aged 18 years or older with CP (n=1511 females, n=1511 males; mean [SD; range] age=48y [19y 2mo; 18–89y]) and all comorbidities in the year 2014. The WCI was developed based on the comorbidities of the CCI and ECI and other relevant comorbidities associated with 2‐year mortality using Cox regression and competing risk analysis. The WCI was examined as unweighted (WCIunw) and weighted (WCIw). The model fit and discrimination (C‐statistic) of each index was assessed using Cox regression. Results Twenty‐seven comorbidities were included in the WCI; seven new comorbidities that were not part of the CCI or ECI were added. The WCIunw and WCIw showed a better model fit and discrimination for 1‐ and 2‐year mortality compared to the CCI and ECI. The WCIunw and WCIw were strong predictors for 1‐ and 2‐year mortality (C‐statistic [95% confidence interval] ranging from 0.81 [0.76–0.85] to 0.88 [0.82–0.94]). Interpretation The new WCI, designed to include clinically relevant comorbidities, provides a better model fit and discrimination of mortality for adults with CP. What this paper adds Common comorbidity indices exclude relevant comorbidities for adults with cerebral palsy (CP). A new comorbidity index for adults with CP was created by harmonizing clinical theory and data‐driven methods. The Whitney Comorbidity Index better predicted 1‐ and 2‐year mortality than other commonly used comorbidity indices.

Whitney Comorbidity Index to monitor health status for adults with cerebral palsy: validation and thresholds to assist clinical decision making

“…The current study provides the ICD-10-CM codes for the WCI comorbidities (Table S1), while our previous study provided the ICD-9-CM codes. 17 Relevant study limitations from using claims-based research for adults with CP have been reported previously. 1,2,[6][7][8]26 It is worth repeating that claims do not contain data on severity of CP, which would provide clinically relevant information.…”

“…Development of the WCI has been previously described. 17 Briefly, the WCI was developed using an iterative process that harmonized clinical theory of relevant comorbidities, consideration of existing validated measures (e.g. Charlson Comorbidity Index), and data-driven approaches to select the final 27 comorbidities (Table S1).…”

“…The Whitney Comorbidity Index (WCI) was recently developed using administrative claims data to monitor health and disease status specifically for adults with CP. 17 The WCI includes 27 clinically relevant comorbidities that are summed; a higher WCI score corresponds to a higher number of these comorbidities. Comparative assessment to other well-established comorbidity indices used for clinical monitoring, including the Charlson 18 and Elixhauser 19 comorbidity indices, found that the WCI better captured the unique morbidity profiles for adults with CP and was a significantly better predictor of mortality.…”

Adults with Cerebral Palsy Require Ongoing Neurologic Care: A Systematic Review

“…In contrast to children with CP, adults with CP are rarely cared for by multidisciplinary teams at large centers, so health service researchers have used administrative datasets to gather large enough samples to estimate the prevalence of comorbidities such as diabetes and hypertension 24 . Attention has now been turned to how these comorbidities interact to produce loss of function and increase mortality 86,87 . Direct neurological assessment of adults with CP can valuably expand on this literature.…”

Comorbidity indices: how should they be developed?

“…Whitney and Kamdar 3 report on the development of a new comorbidity index for adults with CP: the Whitney Comorbidity Index (WCI). It is a CP‐specific index, based on data from an administrative database, used primarily for billing purposes.…”