Comorbidity scores reported in anatomic and reverse total shoulder arthroplasty: a systematic review

Due to the aging population, the number of reverse shoulder arthroplasty (RSA) and anatomic shoulder arthroplasty (TSA) continue to increase annually. Although outcome measures are frequently reported in literature for patients who undergo shoulder arthroplasty, no studies have analyzed reporting of patient comorbidities in this population. The purpose of this study was to evaluate reporting of comorbidity indices in shoulder arthroplasty literature and assess how this reporting may inform management and outcomes.

A database was compiled systematically using PubMed to identify articles pertaining to shoulder arthroplasty published between 2019 and 2021. The search terms, "reverse shoulder arthroplasty" and "anatomic shoulder arthroplasty," were used to identify clinical studies. Non-clinical (e.g., translational and basic science) and review articles were excluded. Included studies were then analyzed for reporting of comorbidity indices.

A total of 199 articles were included in this review and reported comorbidities. Of these, 15.6% (31 of 199) pertained to TSA, while 84.4% (168 of 199) pertained to RSA. Within this review, 57.8% (115 of 199) articles utilized comorbidity scores, while 42.2% (84 of 199) reported only comorbid diagnoses. Among the scores utilized, the American Society of Anesthesiologists (ASA) physical status classification system was the most widely used among both the TSA (52.9%, 9 of 17) and the RSA studies (58.2%, 57 of 98). Additional scores within the RSA literature included the Charlson Comorbidity Index (CCI) (35.3%, 6 of 17), the Charlson Comorbidity Index by Deyo et al. (J Clin Epidemiol. 45(6):613-9, 1992) (CCI-Deyo; 5.9%, 1 of 17), the Modified Charlson Comorbidity Index (modified-CCI) (5.9%, 1 of 17), the Elixhauser et al. (Med Care. 36(1):8-27, 1998) Comorbidity Measure (ECM) (11.8%, 2 of 17), and the Modified Frailty Index (mFI) (5.9%, 1 of 17). With the TSA literature, the additional comorbidity scores included the CCI (30.6%, 30 of 98), the CCI-Deyo (6.1%, 6 of 98), the modified-CCI (1.0%, 1 of 98), the ECM (8.2%, 8 of 98), the Factor-5 modified Frailty Index (mFI-5) (1.0%, 1 of 98), and the mFI (1.0%, 1 of 98).

The reporting of comorbidity indices is an important factor when considering patient outcomes and complications reported in shoulder arthroplasty literature. Although the reporting of these scores appears to be more prevalent in current literature, there is no standard or consistency in terms of which scores are reported. Given this diversity in comorbidity scores, further research is necessary to develop a single standardized score to properly analyze the effect of comorbidities on shoulder arthroplasty patient outcomes.