Systemic treatment with an intramuscular glucocorticoid injection is effective, compared with placebo, in reducing pain in people with hip osteoarthritis for up to 12 weeks, a double-blinded, placebo-controlled, randomized trial suggests.

However, the study found benefit with intramuscular (IM) glucocorticoid injection at 2 weeks only when patients were at rest, and did not find any significant benefit with the injection in reducing pain while walking or in reducing Western Ontario and McMaster University Osteoarthritis Index (WOMAC) pain subscale scores. The report was published in Annals of the Rheumatic Diseases.

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Guidelines recommend intra-articular glucocorticoid injection in patients with painful hip OA, but the efficacy of the invasive procedure is unknown, which prompted Desirée M.J. Dorleijn of Erasmus MC University, Rotterdam, the Netherlands, and her associates to investigate whether an IM glucocorticoid injection is effective as “a less complex alternative treatment for episodes of increased pain in hip OA.”

The multicenter, double-blinded, superiority trial randomized 106 patients with painful hip OA who were not responding to oral analgesics to either 40 mg triamcinolone acetate (n = 52) or placebo injection (n = 54) into the gluteus muscle. Overall, 73 patients (68%) were women, and the average age of the cohort was 64 years. Hip OA symptoms had occurred for at least 1 year in 70% of the patients.

The study’s three primary outcomes of hip pain severity 2 weeks after the injection on a 0-10 scale at rest and during walking and on the WOMAC pain subscale revealed inconsistent results with the treatment.

At the 2-week follow-up, patients who had received the IM glucocorticoid injection had a significant and clinically relevant difference in hip pain at rest (between-group difference = –1.3; 95% confidence interval, –2.3 to –0.3; P = .01). But at this time point there were no significant associations between glucocorticoid injection and hip pain during walking (difference = –0.9; 95% CI, –1.9 to 0.1; P = .07) and WOMAC pain subscale score (difference = –6.1; 95% CI, –13.4 to 1.2; P = .10), the researchers reported.

At 2-week follow-up, recipients of the glucocorticoid injection were significantly more likely to perceive improvement (relative risk = 1.7; 95% CI, 1.1 to 2.7; P = .02) or achieve OMERACT-OARSI level of response (RR = 2.0; 95% CI, 1.1 to 3.6; P = .03).

The authors described this finding as “surprising,” speculating that the 7-point Likert scale used to measure perceived improvement could have resulted in less power.

Nineteen patients in the glucocorticoid group reported 27 nonserious adverse events, compared with 13 patients in the placebo group who reported 18 adverse events.

The authors said the greatest effects of the glucocorticoid injection were seen at 4- to 12-week follow-up (the secondary outcomes of the study), instead of at the 2-week follow-up. For example, at 4-week follow-up, the glucocorticoid injection was associated with a significant hip pain reduction at rest (between-group difference = –1.2; 95% CI, –2.1 to –0.2; P = .01) and during walking (difference = –1.1; 95% CI, –2.0 to –0.2; P = .01). At 6 weeks, the corresponding figures for hip pain reduction were –1.4 at rest (95% CI, –2.4 to –0.5; P = .005) and –1.4 while walking (95% CI, –2.3 to –0.4; P = .004). The between-group differences were still significant at 12 weeks while at rest (difference = –1.2; 95% CI, –2.3 to –0.2; P = .02) and during walking (difference = –1.3; 95% CI, –2.2 to –0.3; P = .01).

Significant differences in favor of the glucocorticoid injection overall occurred on the WOMAC subscale scores for pain, function, and stiffness, as well as total Hip disability and Osteoarthritis Outcome Score for pain and total, intermittent, and constant pain measures on the Intermittent and Constant Osteoarthritis Pain scale. At 12 weeks, the between-group difference on the WOMAC total score was –9.4 (95% CI, –17.8 to –0.9; P = .03).

The researchers said it was surprising that hip pain reduction after IM glucocorticoid injection was still present at a similar degree at 12 weeks since previous studies had shown the effect usually peaked after 1-3 weeks.

“Our findings should be replicated in future research,” they said.

“An IM glucocorticoid injection showed effectiveness in patients with hip OA on one of the three primary outcomes at a 2 weeks post injection ... The effect is probably clinically relevant,” the authors concluded.

The investigators noted that in clinical practice patients are sometimes offered multiple injections per year, whereas in the current study patients received only one injection. There has also been concern that intra-articular glucocorticoid injections could cause toxicity to chondrocytes and potentially lead to OA progression, but the effect of a single IM injection is unknown.

Financial support for the study came from the Dutch Arthritis Foundation and the NutsOhra fund. Two of the authors reported receiving grants from several pharmaceutical companies, research consortia, and foundations.

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SOURCE: Dorleijn D et al. Ann Rheum Dis. 2018 March 7. doi: 10.1136/annrheumdis-2017-212628

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