Incidence of seropositive rheumatoid arthritis in population-based studies in Northern Savo, Finland, during 1980-2020.

The objective is to evaluate the incidence of seropositive rheumatoid arthritis (RA) over 40-year period in Northern Savo, Finland. Data on new seropositive RA patients according to the American College of Rheumatology (ACR) 1987 classification criteria were collected in 2020-2021. In 2020 data on tobacco exposure, patient-reported dental health and living in residences with fluoridated tap water were gathered. Incidence rates were estimated and age- and gender-adjusted to Northern Savo population. The results were compared with data acquired in studies from 1980, 1990, 2000, and 2010. In 2020, 46 seropositive RA patients (21 females and 25 males) were recorded. The crude incidence of seropositive RA fulfilling the ACR 87 criteria in 2020 was 22.3 (95% CI 16.3 to 29.8)/100 000 and age and gender-adjusted 22.3 (95% CI 15.9 to 28.8)/100 000. Tobacco exposure > 5 pack years occurred 18% of females and 56% of males. Only 16% of males were full dentate. A total of 242 incident seropositive RA (age ≥ 16 years, 55% females) were identified in all study years. No differences in the gender-specific incidence rates in each cohort or in incidence between the studies every 10 years were recorded. The incidence of seropositive RA decreased in the age group < 55 years, p = 0.003. There was no change in the incidence of seropositive RA between genders or the study years. A declining trend for occurrence of seropositive RA in the young and early middle-aged population may reflect change in risk factors.

Usage of drugs for cardiovascular diseases is increased in systemic lupus erythematosus (SLE) patients already before diagnosis of SLE.

OBJECTIVES: Systemic lupus erythematosus (SLE) patients are considered as a high-risk population for cardiovascular diseases (CVDs). To explore whether their risk is increased already in preclinical episodes of the disease, we have studied the usage of CVD drugs in incident SLE cases five years before diagnosis of SLE compared to the population controls. METHODS: Adult SLE incident patients (age ≥18 years) from 2004 through 2014 were identified from a nationwide register. The date of granted reimbursement for SLE medication was defined as the date of diagnosis (index day). For each patient, three population controls were matched for age, sex and residence on the index day. The patients and controls were linked to the drug purchase register. All purchases of CVD drugs (Anatomical Therapeutic Chemical (ATC) - codes of C01-C04, C07-C09) and separately C10 were recorded in half-year periods over five years before the index day. RESULTS: A total of 653 SLE patients (mean age 45.7±15.9 years, 83% females) and 1924 population controls were found. Over five years before the index day, the proportion of SLE patients with purchased CVD drugs (46.7%) was greater compared to the controls (28.5%) (p<0.001). The relative risk for purchases started to increase more steeply during the last half-year period before SLE diagnosis. There was no significant difference in lipid-modifying agents between groups. CONCLUSIONS: Our finding that among SLE patients the use of CVD drugs was more common compared to their control population suggests increased CVD risk already before the diagnosis of SLE.

Mortality in SLE patients compared with population controls in Finland in years 2000-2015.

OBJECTIVE: To estimate the risk of mortality in the Finnish incident SLE cohort in a 16-year period compared with the general population. METHODS: Adults with new-onset SLE between 1 January 2000 and 31 December 2014 identified from the national drug reimbursement register and their individually matched controls from the Population Register Centre were followed up until death or 31 December 2015. Data on deaths were retrieved from the national causes of death register. Comorbidities and education were obtained by linkage to the other national registries. RESULTS: A total of 1006 patients with incident SLE and 3005 population controls were found (mean follow-up 8.6 years). Of these, 98 SLE patients subsequently died. Their 5 -, 10-, and 15-year survival rates were 95.0% (95% CI: 93.3, 96.2), 88.8% (86.2, 91.0), and 82.1% (77.6, 85.8), respectively. Crude hazard ratio (HR) was 1.61 (95% CI: 1.26, 2.06), adjusted for education level was almost the same 1.61 (95% CI: 1.26, 2.05). After adjustment for comorbidities and education at baseline, the difference in mortality disappeared: HR 1.14 (95% CI: 0.88, 1.48). The leading causes of death were cardiovascular diseases (CVDs) (33%), malignancies (27%) and neurological diseases (10%). Subhazard ratio for CVD deaths was 1.28 (95% CI: 0.85, 1.93), adjusted for comorbidities and education 0.88 (95% CI: 0.56, 1.39). CONCLUSIONS: These results suggest that the increased mortality in SLE patients is highly associated with comorbidities present at diagnosis. This underlines the importance to screen and treat comorbidities and disease actively without delays.

Metabolic Syndrome, Disease Activity, and Adipokines in Patients With Newly Diagnosed Inflammatory Joint Diseases.

OBJECTIVE: To investigate metabolic syndrome (MetS), disease activity, and adipokine levels among patients with rheumatoid arthritis (RA), spondyloarthritis (SpA), and undifferentiated arthritis (UA) at the time of diagnosis and after 1 year of follow-up. METHODS: Patients with inflammatory joint diseases participating in the Northern Savo 2010 population-based longitudinal epidemiological study were evaluated for components of MetS (by National Cholesterol Education Program's Adult Treatment Panel III) and clinical parameters of disease activity. The adipokines adiponectin, adipsin, resistin, and leptin were measured at baseline and after 1 year of treatment with disease-modifying antirheumatic drugs. RESULTS: Among 176 patients, MetS was detected in 42% of RA, 36% of SpA, and 51% of UA patients. Metabolic syndrome was associated with higher disease activity as measured by patient global assessment in RA and UA patients and increased pain in RA patients. Leptin levels were increased in patients with MetS, showing a linearly increasing trend with the number of components of MetS in SpA and UA, but not in RA. In RA patients, decrease in disease activity correlated with decrease in leptin levels. Resistin did not associate with MetS, but a decrease in resistin correlated with decrease in disease activity in RA and UA. In SpA, increased adiponectin level correlated with relief in disease activity, but not with MetS. CONCLUSIONS: Metabolic syndrome was common in patients with newly diagnosed arthritides and associated with higher disease activity and increased leptin levels. Resistin responded to treatment of arthritis in RA and UA, leptin in RA, and adiponectin in SpA.

Association of rheumatoid arthritis disease activity and antibodies to periodontal bacteria with serum lipoprotein profile in drug naive patients.

Objective: We investigated lipid concentrations, particle sizes and antibodies binding to periodontal bacteria Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis and to malondialdehyde-acetaldehyde (MAA) modified low-density lipoprotein in immunoglobulin (Ig) class A, G and M among patients with newly diagnosed rheumatoid arthritis (RA) in a population-based cohort.Methods: Concentrations and sizes of lipoprotein particles analysed by proton nuclear magnetic resonance spectroscopy and antibody levels to MAA modified low-density lipoprotein were studied at baseline and after one-year of follow-up. Serum Ig A and G class antibodies to periodontal bacteria were determined at baseline.Results: Sixty-three patients were divided into tertiles according to disease activity by disease activity score with 28 joint count and erythrocyte sedimentation rate (ESR) (<3.9, 3.9-4.7, >4.7). Small low-density lipoprotein concentration was lowest in the tertile with the highest disease activity. In high-density lipoprotein, the concentrations of total, medium and small particles decreased with disease activity. The particle size in low-density lipoprotein associated with disease activity and the presence of antibodies to P. gingivalis. Ig G and M antibodies to MAA modified low-density lipoprotein correlated with disease activity. Inflammation associated changes faded by one year.Conclusions: Drug naive RA patients had proatherogenic changes in lipid profiles, but they were reversible, when inflammation diminished.Key messagesPatients with drug naive rheumatoid arthritis showed proatherogenic lipid profiles.Reversible changes in lipid profiles can be achieved as response to inflammation suppression.Active therapy aimed at remission is essential in all patients with rheumatoid arthritis.

Cervical Spine Involvement among Patients with Rheumatoid Arthritis Treated Actively with Treat-to-target Strategy: 10-year Results of the NEO-RACo Study.

OBJECTIVE: To evaluate the development of radiological changes of the cervical spine in patients with rheumatoid arthritis (RA) in the NEO-RACo trial treated with an intensive, remission-targeted combination of conventional synthetic disease-modifying antirheumatic drugs (csDMARD) and additional infliximab (IFX) or placebo (PLA) for the first 6 months. METHODS: Ninety-nine patients with early, DMARD-naive RA were treated with a triple combination of csDMARD and prednisolone, and randomized to double-blindly receive either IFX (FIN-RACo+IFX) or PLA (FIN-RACo+PLA) infusions during the first 6 months. After 2 years the treatment strategies became unrestricted, but the treatment goal was strict NEO-RACo remission. At the 10-year visit, radiographs of the cervical spine were taken of 85 patients (38 in the FIN-RACo+IFX group and 47 in the FIN-RACo+PLA group). The study was registered at ClinicalTrials.gov (NCT00908089). RESULTS: There were 4/85 patients (4.7%) with cervical spine involvement (CSI) by 10 years. Atlantoaxial subluxation was found in 2/85 patients (2.4%), both in the FIN-RACo+IFX group, and none in the FIN-RACo+PLA group. Atlantoaxial impaction was found in 1/85 patients (1.2%) in the FIN-RACo+IFX group. Subaxial subluxation was found in 1/85 patients (1.2%). CONCLUSION: Early and intensive remission-targeted treatment has reduced the incidence of CSI and our results show that intensive treatment also prevents its development in the long run.

Early Targeted Combination Treatment With Conventional Synthetic Disease-Modifying Antirheumatic Drugs and Long-Term Outcomes in Rheumatoid Arthritis: Ten-Year Follow-Up Results of a Randomized Clinical Trial.

OBJECTIVE: The short-term outcomes of remission-targeted treatments of rheumatoid arthritis (RA) are well-established, but the long-term success of such strategies is speculative, as is the role of early add-on biologics. We assessed the 10-year outcomes of patients with early RA treated with initial remission-targeted triple combination of conventional synthetic disease-modifying antirheumatic drugs (csDMARDs), 7.5-mg prednisolone, and additional infliximab (IFX) or placebo infusions. METHODS: Ninety-nine patients with early, DMARD-naive RA were treated with a triple combination of csDMARDs and prednisolone and randomized to double-blind receipt of infusions of either IFX (the Finnish Rheumatoid Arthritis Combination Therapy Trial [FIN-RACo] + IFX) or placebo (FIN-RACo + placebo) during the first 6 months. After 2 years, the treatment strategies became unrestricted, but the treatment goal was strict remission in the TNF-Blocking Therapy in Combination With Disease-Modifying Antirheumatic Drugs in Early Rheumatoid Arthritis (NEO-RACo) study. At 10 years, the clinical and radiographic outcomes and the drug treatments used between 5 and 10 years were assessed. RESULTS: Ninety patients (91%) were followed after 2 years, 43 in the FIN-RACo + IFX and 47 in the FIN-RACo + placebo group. At 10 years, the respective proportions of patients in strict NEO-RACo remission and in Disease Activity Score using 28 joints remission in the FIN-RACo + IFX and FIN-RACo + placebo groups were 46% and 38% (P = 0.46) and 82% and 72% (P = 0.29), respectively. The mean total Sharp/van der Heijde score was 9.8 in the FIN-RACo + IFX and 7.3 in the FIN-RACo + placebo group (P = 0.34). During the 10-year follow-up, 26% of the FIN-RACo + IFX group and 30% of the FIN-RACo + placebo group had received biologics (P = 0.74). CONCLUSION: In early RA, excellent results can be maintained up until 10 years in most patients treated with initial combination csDMARDs and remission-targeted strategy, regardless of initial IFX/placebo infusions.

Impact of early systemic lupus erythematosus on work disability-results from the Finnish nationwide register 2000-2007.

Objectives of this study were to examine work disability (WD) and its leading causes in incident SLE patients. Data were derived from the Finnish nationwide registries to identify all non-retired, 18 to 64-year-old incident SLE patients between 2000 and 2007. Sick benefits and WD pensions and the causes for them were monitored until the end of 2008. A total of 446 working-aged, incident SLE patients available for work force (mean age 42 ± 13 years, 89% females) were found. During the follow-up (median 5.3 years), WD pension was granted to 27 patients. The most common cause was SLE itself (14 patients, 52%), with cumulative incidence of 3.4% (95% CI 1.9 to 5.8) in 5 years and 5.0% (95% CI 3.0 to 8.5) in 8 years, followed by musculoskeletal and psychiatric causes. The age- and sex- adjusted incidence ratio for WD pension in SLE patients due to any cause was 5.4 (95% CI 3.7 to 7.9) compared to the Finnish population. The mean number of WD days was 32 (95% CI 28 to 35) per patient-year among all SLE patients during the follow-up. The study concludes that SLE patients have an increased risk for WD already in early course of the disease.

Glycoprotein YKL-40: A potential biomarker of disease activity in rheumatoid arthritis during intensive treatment with csDMARDs and infliximab. Evidence from the randomised controlled NEO-RACo trial.

OBJECTIVE: YKL-40, a chitinase-like glycoprotein associated with inflammation and tissue remodeling, is produced by joint tissues and recognized as a candidate auto-antigen in rheumatoid arthritis (RA). In the present study, we investigated YKL-40 as a potential biomarker of disease activity in patients with early RA at baseline and during intensive treatment aiming for early remission. METHODS: Ninety-nine patients with early DMARD-naïve RA participated in the NEO-RACo study. For the first four weeks, the patients were treated with the combination of sulphasalazine, methotrexate, hydroxychloroquine and low dose prednisolone (FIN-RACo DMARD combination), and subsequently randomized to receive placebo or infliximab added on the treatment for further 22 weeks. Disease activity was evaluated using the 28-joint disease activity score and plasma YKL-40 concentrations were measured by immunoassay. RESULTS: At the baseline, plasma YKL-40 concentration was 57 ± 37 (mean ± SD) ng/ml. YKL-40 was significantly associated with the disease activity score, interleukin-6 and erythrocyte sedimentation rate both at the baseline and during the 26 weeks' treatment. The csDMARD combination decreased YKL-40 levels already during the first four weeks of treatment, and there was no further reduction when the tumour necrosis factor-α antagonist infliximab was added on the combination treatment. CONCLUSIONS: High YKL-40 levels were found to be associated with disease activity in early DMARD-naïve RA and during intensive treat-to-target therapy. The present results suggest YKL-40 as a useful biomarker of disease activity in RA to be used to steer treatment towards remission.

Intra-articular glucocorticoid injections should not be neglected in the remission targeted treatment of early rheumatoid arthritis: a post hoc analysis from the NEO-RACo trial.

OBJECTIVES: To study the effects of neglecting intra-articular glucocorticoid injections (IAGCIs) into swollen joints in early rheumatoid arthritis (RA). METHODS: Ninety-nine patients with early, DMARD naive RA were treated, aiming at remission, with methotrexate, sulfasalazine, hydroxychloroquine, low-dose oral prednisolone and, when needed, IAGCIs for 2 years, and randomised to receive infliximab or placebo from weeks 4 to 26. During each of the 15 study visits, patients were scored retrospectively 0.2-0.4 points (depending on the number of non-injected joints) if IAGCIs to all swollen joints were not given. Patients were divided into tertiles by their cumulative scores for neglected injections (CSNI) over 24 months. 28-joint disease activity score (DAS28) area under the curve (AUC) between 0-24 months, remission rates, changes in quality of life, and radiological changes during the follow-up were assessed. Trends across tertiles of CSNI were tested with generalised linear models. RESULTS: Higher CSNI was associated with lower strict remission rates (p=0.005), and lower quality of life (p=0.004) at 24 months, and higher DAS28 AUC (p<0.001) during the follow-up. At 24 months, DAS28 remission rates were 90%, 93% and 76% (p=0.081), and strict remission rates were 74%, 77% and 39% by tertiles of CSNI. No significant differences were observed in radiological progression (p=0.089). IAGCIs were well tolerated. CONCLUSIONS: Neglecting IAGCIs into swollen joints is associated with lower remission rates, higher disease activity, and lower quality of life. Hence, IAGCIs should be used as an integral part of the targeted treatment of early RA.

Automated immunoassays for the autoantibodies to carbamylated or citrullinated telopeptides of type I and II collagens.

BACKGROUND: The aim of the study was to describe automated immunoassays for autoantibodies to homocitrulline or citrulline containing telopeptides of type I and II collagen in various disease categories in an early arthritis series. METHODS: Serum samples were collected from 142 patients over 16 years of age with newly diagnosed inflammatory joint disease. All samples were analyzed with an automated inhibition chemiluminescence immunoassay (CLIA) using four different peptide pairs, each consisting of a biotinylated antigen and an inhibiting peptide. Assays were performed with an IDS-iSYS analyzer. Autoantibodies binding to homocitrulline and citrulline containing C-telopeptides of type I (HTELO-I, TELO-I) and type II collagens (HTELO-II, TELO-II) were analyzed. RESULTS: The mean ratio of HTELO-I inhibition in seropositive and seronegative rheumatoid arthritis (RA) was 3.07 (95% CI 1.41-11.60), p=0.003, and in seropositive and seronegative undifferentiated arthritis (UA) 4.90 (1.85-14.49), p<0.001. The respective mean ratios in seropositive and seronegative RA and UA were in TELO-I 8.72 (3.68-58.01), p<0.001 and 3.13 (1.49-6.16), p=0.008, in HTELO-II 7.57 (3.18-56.60), p<0.001 and 2.97 (1.23-6.69), p=0.037, and in TELO-II 3.01 (1.30-9.51), p=0.002 and 3.64 (1.86-7.65), p=0.008. In reactive arthritis, ankylosing spondylitis, psoriatic arthritis and unspecified spondyloarthritis the inhibition levels were similar to those observed in seronegative RA or UA. CONCLUSIONS: Autoantibodies binding to homocitrulline or citrulline containing telopeptides of type I and II collagen did not differ significantly. They were highest among patients with seropositive disease and they differentiated seropositive and seronegative arthritis.

Incidence of systemic lupus erythematosus in Finland, 2000-2007, a nationwide study.

OBJECTIVES: To determine the age- and sex-specific incidence rates of systemic lupus erythematosus (SLE) in Finland. METHODS: The incident cases were identified through diagnostic register searches for SLE on the nationwide database of the Social Insurance Institution. RESULTS: During the 8-year study period 599 incident cases occurred (518 females, 81 males). The mean annual incidence rate of SLE for adults was 1.69 per 100,000 (95% CI 1.56-1.84) and was highest among females aged 40-59 years. The gender incidence rate ratio was 6.43 (95% CI 5.06-8.26). The incidence for children was 0.39 (95% CI 0.27-0.55). CONCLUSIONS: The incidence of SLE was lower compared to the countries at the same latitudes. SLE in children remained a rarity.

Failure in longterm treatment is rare in actively treated patients with rheumatoid arthritis, but may be predicted by high health assessment score at baseline and by residual disease activity at 3 and 6 months: the 5-year followup results of the randomized clinical NEO-RACo trial.

OBJECTIVE: With modern initial aggressive combination treatments with synthetic disease-modifying antirheumatic drugs (sDMARD), most patients with rheumatoid arthritis (RA) achieve remission, have marginal radiographic progression, and sustain normal function. Here we aim to identify the patients failing these targets even after aggressive treatment. METHODS: Ninety-nine patients with early, active RA were treated with a combination of 3 sDMARD and prednisolone (PRD), and either infliximab or placebo infusions during the first 6 months, aiming at strict remission. After 24 months, the treatments became unrestricted. At 60 months, 4 evident clinical features of treatment failure were defined: area under curve (AUC) between 6-60 months for disease activity score assessing 28 joints > 2.6; AUC 6-60 for health assessment questionnaire > 0.5; progression in total Sharp/van der Heijde score 0-60 months > 3 units; and need of PRD or biologic DMARD treatment at 60 months. RESULTS: A total of 93 patients were followed up for 60 months. Of them, 45 had no features of treatment failure, 30 had 1, 10 had 2, 7 had 3, and 1 patient had all 4 features. Having 2-4 features of treatment failure at 5 years was predicted by the health assessment score at baseline, and by even low residual disease activity at 3 and 6 months. CONCLUSIONS: Only 20% of the patients with RA treated early with combination sDMARD and PRD have more than 1 clinical feature of treatment failure at 60 months. Residual clinical disease activity at 3-6 months was the most important predictor for identifying these patients. The study was registered at www.clintrials.gov (NCT00908089).

Targeted treatment with a combination of traditional DMARDs produces excellent clinical and radiographic long-term outcomes in early rheumatoid arthritis regardless of initial infliximab. The 5-year follow-up results of a randomised clinical trial, the NEO-RACo trial.

OBJECTIVE: To study whether adding initial infliximab to remission-targeted initial combination-DMARD treatment improves the long-term outcomes in patients with early rheumatoid arthritis (RA). METHODS: Ninety-nine patients with early, DMARD-naïve RA were treated with a triple combination of DMARDs, starting with methotrexate (max 25 mg/week), sulfasalazine (max 2 g/day), hydroxychloroquine (35 mg/kg/week), and with prednisolone (7.5 mg/day), and randomised to double blindly receive either infliximab (3 mg/kg; FIN-RACo+INFL) or placebo (FIN-RACo+PLA) infusions during the first 6 months. After 2 years the treatment strategies became unrestricted, but the treatment goal was strict ACR remission. At 5 years the clinical and radiographic outcomes were assessed. RESULTS: Ninety-one patients (92%) were followed up to 5 years, 45 in the FIN-RACo+INFL and 46 in the FIN-RACo+PLA groups. At 5 years, the respective proportions of patients in strict ACR and in disease activity score 28 remissions in the FIN-RACo+INFL and FIN-RACo+PLA groups were 60% (95% CI 44% to 74%) and 61% (95% CI 45% to 75%) (p=0.87), and 84% (95% CI 71% to 94%) and 89% (95% CI 76% to 96%) (p=0.51). The corresponding mean (SD) total Sharp/van der Heijde scores at 5 years were 4.3 (7.6), and 5.3 (7.3), while the respective mean Sharp/van der Heijde scores changes from baseline to 5 years were 1.6 (95% CI 0.0 to 3.4) and 3.7 (95% CI 2.2 to 5.8) (p=0.13). CONCLUSIONS: In early RA, targeted treatment with a combination of traditional DMARDs and prednisolone induces remission and minimises radiographic progression in most patients up to 5 years; adding initial infliximab for 6 months does not improve these outcomes.

Infliximab for 6 months added on combination therapy in early rheumatoid arthritis: 2-year results from an investigator-initiated, randomised, double-blind, placebo-controlled study (the NEO-RACo Study).

OBJECTIVE: Early treatment of patients with rheumatoid arthritis (RA) with combination treatment starting with methotrexate, sulfasalazine, hydroxychloroquine and prednisolone (FIN-RACo strategy) is superior to monotherapy. A study was undertaken to determine whether infliximab (INFL) added to intensified FIN-RACo treatment for the initial 6 months improves the 2-year outcome. METHODS: 99 patients with early untreated active RA were enrolled in an investigator-initiated, randomised, double-blind, multicentre, parallel-group trial. Primary outcomes were remission and radiological changes at 2 years. All patients started with FIN-RACo. In addition, they were randomised to receive INFL or placebo (Pla) from weeks 4 to 26. RESULTS: At 24 months, 66% and 53%, respectively, of the patients in the FIN-RACo+INFL and FIN-RACo+Pla groups were in remission according to the modified American College of Rheumatology (ACR) criteria (p=0.19), 26% and 10% were in sustained modified ACR remission (p=0.042) and 82% in both groups were in remission by 28-joint disease activity score (not significant). Mean changes in the total Sharp-van der Heijde score were 0.2 and 1.4, respectively (p=0.0058). CONCLUSIONS: Most patients with early active RA achieve clinical remission and develop negligible joint damage with the intensified FIN-RACo regimen. Adding INFL for the first 6 months delays radiological progression.

[Chest, skin and joint symptoms of a middle-aged man]. / Keski-ikäisen miehen rintakehä- iho- ja niveloireet.

A middle-aged male patient was examined due to chest pain. At the same time blisters appeared on his palms and soles of the foot. Radiologic examinations revealed lesions in the thoracic vertebral bodies, in the first rib and in the sternum. Inflammatory markers were elevated in the blood. The patient subsequently developed arthritis in a previously injured knee.

[Adverse muscle effects of a podofyllotoxin-containing cytotoxic drug product with simvastatin]. / Podofyllotoksiinia sisältävän solunsalpaajavalmisteen ja simvastatiinin lihashaitat.

With the ageing population, drug interactions pose an increasing challenge to health professionals. We describe four patients, for whom concurrent administration of a podofyllotoxin-containing cytotoxic drug product and simvastatin caused severe adverse effects on muscles, including muscle pain, soreness or fatigue or weakness, and in some patients also disintegration of muscle tissue, i.e. rhabdomyolysis. The metabolism of both drugs proceeds via the common CYP3A4 enzyme pathway.

Declining trend in the incidence of rheumatoid factor-positive rheumatoid arthritis in Finland 1980-2000.

OBJECTIVE: To investigate trends in the incidence of rheumatoid arthritis (RA) in Finland. METHODS: We studied all the subjects entitled to receive drug reimbursement for chronic inflammatory joint diseases in 5/21 central hospital districts (population base about 1 million adults) in Finland during 2000. The incidence rates and the mean age at disease onset were compared with those from 1980, 1985, 1990, and 1995. RESULTS: A total of 714 subjects were entitled to drug reimbursement for chronic inflammatory joint disease that had started at the age of 16 or over. Of them, 321 satisfied the American College of Rheumatology classification criteria for RA, 198 had spondyloarthropathy, and 195 had undifferentiated oligo- or polyarthritis. The incidence of RA was 29.1/100,000 (95% CI 26.0-32.5); the figures for rheumatoid factor (RF)-positive RA and RF-negative RA were 18.2 (95% CI 15.8-21.0) and 10.8 (95% CI 9.0-12.9)/100,000, respectively. The incidence of RA was 36.9 (95% CI 32.1-42.2)/100,000 among women and 20.8 (95% CI 17.2-25.1)/100,000 among men. The age- and sex-adjusted incidence rate ratio declined from 1.00 in the referent year 1980 to 0.55 (95% CI 0.46-0.66) in 2000. A declining trend was evident for the incidence of RF-positive RA (p < or = 0.001). CONCLUSION: We verified the declining trend for the incidence of RF-positive RA in both sexes in Finland. Although the etiology of RA remains unknown, public health measures may reduce the risk of RA in the general population.