Fewer lifestyle-related chronic diseases and higher out-of-pocket costs are predictive of favorable response to intra-articular platelet-rich plasma injections in the treatment of knee osteoarthritis.

Abstract

Platelet-rich plasma (PRP) is increasingly used for treatment of knee osteoarthritis, but there is limited understanding regarding which patients will benefit most. The impact of lifestyle-related chronic diseases, which are linked to systemic inflammation, and behavioral factors, such as agreed-upon out-of-pocket costs, have been underevaluated as predictors of PRP response. To investigate patient-specific factors for favorable response to intra-articular PRP injection in treating knee osteoarthritis, with a focus on lifestyle-related chronic disease burden (ie, hypertension, hyperlipidemia, type-2 diabetes, obstructive sleep apnea, anxiety/depression, gastroesophageal reflux disease, autoimmune disease, some cancers) and patients' agreed-upon out-of-pocket costs. Retrospective review. Tertiary orthopedic institution. Patients who underwent first-time, single, intra-articular PRP injections for symptomatic knee osteoarthritis. Not applicable. Numerical rating scale or visual analog scale pain scores were collected at baseline and at 3-6 months post injection. Patients who achieved minimal clinically important reductions of 20% in pain score, or overall pain improvement of ≥60%, were classified as responders. Two hundred nine initial intra-articular PRP injections in 199 unique patients with symptomatic knee osteoarthritis were included. The mean age was 65 ± 11 years (113/209 [54%] female). A majority (91%) of the cohort had more than one lifestyle-related chronic disease, with the most common being hyperlipidemia; 74% had two or more lifestyle-related chronic diseases. Of the 209 injections, 85 (41% [95% confidence interval (CI): 34%-48%]) were classified as responders. Obstructive sleep apnea was more prevalent in nonresponders than responders (9% vs. 1%; p = .019). On multivariable logistic regression, having fewer than two lifestyle-related chronic diseases (odds ratio [OR]: 2.06 [95% CI, 1.01-4.16]; p = .046) or paying higher out-of-pocket procedure costs (OR: 1.28 [95%CI, 1.04-1.59] per $500-increase in out-of-pocket cost; p = .022) was associated with greater likelihood of positive response to PRP injection at 3-6 months. The effectiveness of PRP injections for knee osteoarthritis may be reduced in patients with higher cumulative disease burden of lifestyle-related chronic diseases, as well as in patients paying lower out-of-pocket procedure costs.