The Cost of Knee Osteoarthritis: Physical Therapy vs Glucocorticoid Injection

Daniel Rhon, DPT, DSc, PhD

A new study found that patients with knee osteoarthritis who received physical therapy (PT) gained more quality-adjusted life-years compared with those who received glucocorticoid injection. When examining the costs associated with knee care, the totals were similar between the 2 groups.

Knee osteoarthritis is generally treated with either physical therapy or glucocorticoid injections, or both. Available data have indicated that most patients receive one or the other, which suggests that they’re competing interventions.

A team of investigators, led by Daniel Rhon, DPT, DSc, PhD, Department of Rehabilitation Medicine, Brooke Army Medical Center, Department of Rehabilitation Medicine, Uniformed Services University of Health Sciences, aimed to examine the incremental cost-effectiveness between physical therapy and intra-articular glucocorticoid injection as initial treatment strategies for knee osteoarthritis.

The Motivation

Osteoarthritis accounts for a disproportionate level of disability and health care expenditures worldwide, and is the most common type of arthritis. In the US, it ranks as the eighth most expensive to manage of 154 health conditions.

In the last 70 years, the prevalence of osteoarthritis in the knee has doubled. It can begin early in life with a slow progression, which may allow for opportunities for nonsurgical treatment.

The American College of Rheumatology guidelines for treatment include 6 strongly recommended and 8 conditionally recommended non pharmacological interventions, as well as 7 pharmacological treatments.

Patients and clinicians have many options to consider when creating the optimal treatment plan. With cost and accessibility being key factors in decision-making, investigators decided to look at the cost-effectiveness of 2 of the primary treatments for knee osteoarthritis.

A recent trial deemed physical therapy clinically more effective than glucocorticoid injection, and also more expensive when comparing a typical PT course ($557-$919 for an evaluation and 7 30 minute PT sessions) to a single injection ($99-$172 for a primary care office visit and injection procedure).

In this study, investigators aimed to assess the cost-effectiveness of physical therapy compared with glucocorticoid injection from the health care perspective.

The Study

An economic evaluation was conducted using patient-level data from a randomized clinical trial that captured health care system costs, including knee-specific care costs, and quality-adjusted life-years (QALYs), which is a 2-dimensional metric that incorporates both health-related quality of life and survival, according to investigators.

Patients that met clinical and radiographic criteria for knee osteoarthritis established by the American College of Rheumatology were recruited from October 2012-May 2017 and and were followed up until May 2018.

Investigators randomly assigned 78 patients to receive intra-articular glucocorticoid injections and 78 patients to receive physical therapy. The primary outcome was measured by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) as the difference in the group’s total score at 1 year.

The Military Health System Data Repository (MDR) was used to source all costs of care. The Military Health System is a closed, single-payer government health system.

The Results

Effectiveness was measured using quality-adjusted life-years between groups and the results were significant. Patients who participated in physical therapy achieved 0.08 more QALYs than those who received corticosteroid injections (95% CI, 0.02-0.13; P=.03).

For knee-related medical costs, the mean numbers of the groups at the 1 year follow-up were similar when unadjusted for any covariates. The cost for the glucocorticoid group was $2113, and $2131 for the physical therapy group.

However, when the costs were adjusted for age, body mass index, female sex, smoking status, and radiographic severity, patients in the physical therapy group spent an adjusted mean of $615 more than those in the glucocorticoid injection group, but the mean difference was not significant.

In terms of total medical costs for any reason, patients in the physical therapy group spent and adjusted mean of $2145 more than patients in the glucocorticoid injection group (95% CI, $12-$4279; P=0.49).

When looking at the quality to cost-effectiveness together, patients in the physical therapy group achieved a mean QALY of 0.076 more at a mean cost of $615 higher for knee-related medical costs compared with the patients who received the injections.

These results suggest that physical therapy is a cost-effective intervention despite higher initial costs than glucocorticoid injection.

“Costs, in both time and dollars, are likely relevant decision factors driving the use of each treatment,” investigators wrote. “Physical therapy in this trial involved a typical course of 8 visits during 4 weeks, whereas the injection can be delivered during the initial consultation with guidance for 72 hours of reduced patient activity.”

The study “Cost-effectiveness of Physical Therapy vs Intra-articular Glucocorticoid Injection for Knee Osteoarthritis”, was published in JAMA Network Open.