Impact of comorbidities and functional impairment on 5-year loss of health utility in patients with lower-limb osteoarthritis in the KHOALA cohort

The Effect of Changes in the Body Mass Index After Total Knee and Hip Arthroplasty on Patient Functional Scores

Introduction High body mass index (BMI) often causes immobility and functional impairment before arthroplasty. Patients expect weight loss post-surgery due to increased mobility, but paradoxically, studies show that weight may not decrease and might even increase postoperatively. This study aims to evaluate if patients lose weight after total knee arthroplasty (TKA) and total hip arthroplasty (THA) and to examine the impact of BMI change on functional scores. Methods We analyzed 459 patients who underwent primary TKA and THA between January 2018 and December 2022, with a two-year follow-up. Patients with incomplete data or bariatric surgery were excluded. Demographic characteristics, BMI, Oxford scores, comorbidities, corticosteroid use, physiotherapy, and surgery type (unilateral or bilateral) were assessed. Results Patients showed a significant increase in BMI postoperatively, especially those with comorbidities and younger age. Throughout the entire follow-up period, the BMI value of the knee group was higher than that of the hip group. Comorbidities significantly influenced BMI increase, while corticosteroid use and physiotherapy follow-up did not. Oxford scores improved postoperatively, but the presence of comorbidities and physiotherapy follow-up negatively impacted score changes. A negative correlation between BMI change and Oxford score change was observed (p = 0.013), indicating that increased BMI is associated with less improvement in functional scores. This correlation was significant for hip arthroplasty patients (p = 0.000), but not for knee arthroplasty patients (p = 0.822). Conclusions BMI changes post-TKA and THA are influenced by various clinical and demographic factors. Increased BMI negatively affects functional outcomes, particularly in hip arthroplasty patients. Comorbidities significantly influenced weight gain, while oral corticosteroid use had no notable effect on BMI. Patients undergoing bilateral procedures experienced lower BMI increases. The hip group gained more weight, but the knee group's BMI remained higher throughout the follow-up. In terms of Oxford scores, comorbidities, corticosteroid use, affected joints, and age did not significantly impact outcomes. Patients under physiotherapist supervision showed smaller score increases. While bilateral procedure patients achieved higher scores, simultaneous bilateral procedures did not lead to greater increases. These findings highlight the importance of weight control and rehabilitation in improving postoperative recovery and quality of life.

Association of Baseline Cardiovascular Diseases with 5-Year Knee and Hip Osteoarthritis Progression in Non-Obese Patients: Data from the KHOALA Cohort

We aimed to explore the relationship between comorbidities and the structural progression in symptomatic knee and/or hip osteoarthritis (OA) patients. We analyzed the 5-year outcome of non-obese participants (body mass index (BMI) < 30 kg/m²) from the KHOALA cohort having symptomatic hip and/or knee OA (Kellgren and Lawrence (KL) ≥ 2). The primary endpoint was radiological progression, defined as ΔKL ≥ 1 of the target joint at 5 years. The secondary outcome was the incidence of total knee or hip replacement over 5 years. Dichotomous logistic regression models assessed the relationship of comorbidities with KL progression and joint replacement while controlling for gender, age and BMI. Data from 384 non-obese participants were analyzed, 151 with hip OA and 254 with knee OA. At 5 years, cardiovascular diseases (CVD) were significantly associated with the 5-year KL change in both knee (OR = 2.56 (1.14–5.78), p = 0.02) and hip OA (OR = 3.45 (1.06–11.17), p = 0.04). No significant relationship was found between any type of comorbidities and knee or hip arthroplasty. This 5-year association between CVD and radiological progression of knee and hip OA in non-obese participants argue for an integrated management of CVD in knee and hip OA non-obese patients.

Development and Testing of Compatible Diagnosis Code Lists for the Functional Comorbidity Index: International Classification of Diseases, Ninth Revision, Clinical Modification and International Classification of Diseases, 10th Revision, Clinical Modification

BACKGROUND

The Functional Comorbidity Index (FCI) was developed for community-based adult populations, with function as the outcome. The original FCI was a survey tool, but several International Classification of Diseases (ICD) code lists-for calculating the FCI using administrative data-have been published. However, compatible International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and ICD-10-CM versions have not been available.

OBJECTIVE

We developed ICD-9-CM and ICD-10-CM diagnosis code lists to optimize FCI concordance across ICD lexicons.

RESEARCH DESIGN

We assessed concordance and frequency distributions across ICD lexicons for the FCI and individual comorbidities. We used length of stay and discharge disposition to assess continuity of FCI criterion validity across lexicons.

SUBJECTS

State Inpatient Databases from Arizona, Colorado, Michigan, New Jersey, New York, Utah, and Washington State (calendar year 2015) were obtained from the Healthcare Cost and Utilization Project. State Inpatient Databases contained ICD-9-CM diagnoses for the first 3 calendar quarters of 2015 and ICD-10-CM diagnoses for the fourth quarter of 2015. Inpatients under 18 years old were excluded.

MEASURES

Length of stay and discharge disposition outcomes were assessed in separate regression models. Covariates included age, sex, state, ICD lexicon, and FCI/lexicon interaction.

RESULTS

The FCI demonstrated stability across lexicons, despite small discrepancies in prevalence for individual comorbidities. Under ICD-9-CM, each additional comorbidity was associated with an 8.9% increase in mean length of stay and an 18.5% decrease in the odds of a routine discharge, compared with an 8.4% increase and 17.4% decrease, respectively, under ICD-10-CM.

CONCLUSION

This study provides compatible ICD-9-CM and ICD-10-CM diagnosis code lists for the FCI.