Opioid use among patients with inflammatory arthritis peaks before diagnosis and rapidly decreases after prescription of antirheumatic therapy, according to results of a Finnish population study published in The Journal of Rheumatology.
Using data collected from the Finnish national registry, investigators aimed to assess the epidemiology of opioid use in patients with early inflammatory arthritis and determine whether accurate antirheumatic treatment effectively reduces opioid use.
A total of 12,115 adult patients were included in the study, among whom 6186 had seropositive rheumatoid arthritis (RA; 66% women), 2970 had seronegative RA (67% women), and 2959 had undifferentiated arthritis (67% women). Each patient with arthritis was matched with 3 control participants. The dates when the refund for antirheumatic drugs was issued served as a proxy indicator for the date of inflammatory arthritis diagnosis, or the index date of the study.
For all arthritis groups, opioid purchases peaked during the 3 months before the index date. Compared with control participants, patients with seropositive RA (risk ratio [RR], 2.81; 95% CI, 2.55-3.09), seronegative RA (RR, 3.06; 95% CI, 2.68-3.49), and undifferentiated arthritis (RR, 4.04; 95% CI, 3.51-4.65) were at significantly higher risk for opioid use.
After the index date, opioid purchases sharply declined among patients with arthritis, but were still higher than among the control participants. The difference in opioid use compared with control participants was highest in the undifferentiated arthritis group (RR, 2.51; 95% CI, 2.15-2.93), but was also seen in the seropositive RA (RR, 1.38; 95% CI, 1.23-1.58) and seronegative RA groups (RR, 1.91; 95% CI, 1.63-2.24). No drop in opioid purchases was observed in the control group.
Long-term opioid use, defined by opioid purchases in at least 3 quarters of the year before and after the index date, was more common among patients with inflammatory arthritis compared with control participants. Patients with undifferentiated arthritis were more likely to be long-term opioid users (RR, 3.5) than patients with seropositive (RR, 1.3) or seronegative RA (RR, 1.9).
Researchers noted that the lack of clinical and health behavioral data and patient-level pain scores represented limitations of the study.
“In our study, opioid use especially among patients with seropositive RA decreased rapidly once the diagnosis had been set, presumably indicating initiation of antirheumatic drugs and effective disease control with [disease-modifying antirheumatic drugs],” the researchers concluded. “The same progress was seen in seronegative RA and somewhat less sharply in [undifferentiated arthritis].”
Investigators also noted that the rates of opioid use in patients with arthritis were lower than those previously reported from other countries.
Muilu P, Rantalaiho V, Kautiainen H, Virta LJ, Puolakka K. Opioid use among patients with early inflammatory arthritides compared to the general population [published online October 15, 2019]. J Rheumatol. doi:10.3899/jrheum.190355