The complexity score: towards a clinically-relevant, clinician-friendly measure of patient multi-morbidity

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Ross Edward Grant Upshur
Li Wang
Rahim Moineddin
Jason Nie
C. Shawn Tracy


Rationale and Objectives: The population is rapidly aging and concurrent chronic diseases are increasing rapidly in the developed world. Health systems, clinicians, patients and care givers are challenged by the provision of care in this complex environment. Clinical assessment tools are needed to optimize management and facilitate informed decision-making by patients and care givers. We propose and evaluate a simple tool called the complexity score and evaluate its properties in terms of its distribution in a senior population in an academic family practice and assess its association with health services utilization.Methods: We performed a retrospective chart audit of 2,450 patients aged 65 and older seen in an academic family practice in Ontario, Canada. We calculated the complexity score for each patient and analyzed the scores by age and gender. Using logistic and Poisson regression we evaluated the association of age, gender, marital status and complexity score with hospital admission (surgical and medical), emergency room visits and family practice visits.Results: The complexity score of the practice was high. Overall median complexity score increased with age (65-69: 12, 85+: 16). Age, gender and complexity score were independently and statistically significantly associated with increased hospitalizations, emergency room visits and family physician visits. The OR for the complexity score was substantially increased for the highest complexity score in comparison to the reference group: OR ER visit: 6.5 (95% CI: 3.798-11.058), OR Hospitalization:12.08 (95% CI: 6.404-22.79). Age alone at most doubled the OR for these associations.Conclusions: Multi-morbidity is common amongst older adults in an academic family practice. The complexity score is a simple to calculate measure that has the capacity to inform clinicians and patients on anticipated health service utilization. Further prospective studies are required to replicate the strong and significant associations described in this study. Further measurement tools that capture patient wellbeing and functional status are required to compliment this measure.

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