Epidemiological incidence studies are important in the planning of health care resources. In recent decades, the pharmacotherapy for IAs has intensified with the introduction of new disease-modifying anti-rheumatic drugs (DMARDs) to the market. The current treatment recommendations for early IA aim at active DMARD initiation and rapid disease remission. Despite the intensification of drug therapy, IA patients’ pain management remains a challenge. Increasing opioid use is causing worldwide concern, and there is insufficient evidence for the benefits of opioids in the management of arthritis pain.
The objectives of this study were to investigate the trends in the incidences of IAs in Finland during this millennium, and to obtain data on IA patients’ early DMARD therapies and the implementation of treatment recommendations, as well as the patients’ analgetic use, with a special emphasis on opioids.
The data were collected from the registries maintained by the Finnish Social Insurance Institution, and patients were compared with general population controls matched for age, gender, and place of residence by the Population Register Centre. In terms of incidence, a wider range of IAs was observed, whereas the other three substudies focused on rheumatoid arthritis (RA), undifferentiated arthritis (UA), and axial spondyloarthritis (axSpA).
It turned out that between 2000 and 2014, the age-standardized total incidence of IAs in Finland was 115 for women and 70/100,000 for men. Between the five- year cohorts 2000-2004 and 2010-2014, the incidence of axSpA, UA, and psoriatic arthritis increased significantly. No significant change was observed in the incidence of seropositive RA, whereas the incidence of seronegative RA declined. The mean age at diagnosis of an IA decreased in women from 53 to 51 years.
The treatment of early RA and UA was initiated actively in Finland. At one month from diagnosis, more than 90% of RA patients and nearly as many UA patients had started a conventional synthetic (cs) DMARD, most commonly methotrexate (MTX). The triple combination of csDMARDs recommended in the Current Care Guidelines was initiated by 22% of seropositive RA patients. The use of self-injected biological (b) DMARDs was low during the first year of follow-up. Treatment of axSpA was started with a csDMARD, most commonly sulfasalazine or MTX, and less than 14% of the patients started a self-injected bDMARD within a year of diagnosis.
Individual opioid purchases as well as long-term opioid use were more common among IA patients compared to the population controls, and this difference was 5- 14% depending on the IA diagnosis. The risk ratio of opioid purchases among IA patients compared to the controls was greatest in the three-month period prior to diagnosis, and it decreased after the assumed DMARD initiation during the one-year follow-up, especially among seropositive RA patients. Although the axSpA patients’ mean age at diagnosis was lower than in the other studied IA groups, a larger proportion of them (30% a year before and 22% a year after the diagnosis) used opioids compared to RA and UA patients.
Among Finnish IA patients, the opioid use concentrated on mild opioids and was relatively less common than in most other Western countries. AxSpA patients’ opioid consumption (in defined daily doses) decreased during the 12-months of follow-up among those to whom bDMARDs were started between 2010 and 2015.
In conclusion, during the 15-year observation period, the total incidence of IAs increased somewhat. The treatment of RA was initiated early and often with MTX- based combination therapy. In the early treatment of axSpA, the proportions of users of self-injected bDMARDs were quite low, but the initiation of a bDMARD appeared to reduce these patients’ opioid consumption.
The risk for opioid use was higher among IA patients compared to their population controls. Taken together, the population’s increasing life expectancy and the fact that IA patients’ treatment often requires long-term monitoring in rheumatology clinics, the burden caused by IAs on the health care system and especially on specialist care will probably increase in the future.
The doctoral dissertation of Med.Lic. Paula Muilu in the field of internal medicine titled Inflammatory Arthritides in Finland – Incidence, Early Treatment and Opioid Use will be publicly examined at the Faculty of Medicine and Health Technology of Tampere University at 1 o'clock p.m. on Friday 28 May, 2021. Docent Markku Hakala from the University of Oulu will be the opponent while Professor (tenure track) Vappu Rantalaiho will act as the custos.
The event can be followed via remote connection
The dissertation is available online at
http://urn.fi/URN:ISBN:978-952-03-1951-9