Changes and sex differences in patient reported outcomes in rheumatoid factor positive RA-results from a community based study

Sex Differences in Pain and Quantitative Sensory Testing in Patients With Rheumatoid Arthritis

OBJECTIVE

Women with rheumatoid arthritis (RA) have higher pain and worse functional outcomes compared to men, even when treated with similar medications. The objective of this study was to identify sex differences in pain intensity, pain interference, and quantitative sensory tests (QST), which are independent of inflammation, in patients with RA.

METHODS

This study is a post hoc analysis of participants in the Central Pain in Rheumatoid Arthritis cohort. Pain intensity was assessed using a 0-10 numeric rating scale. Pain interference was measured using a Patient-Reported Outcomes Measurement Information System computerized adaptive test. QST included pressure pain detection thresholds, temporal summation, and conditioned pain modulation. Women and men were compared using multiple linear regression, adjusted for age, education, race, research site, depression, obesity, RA disease duration, swollen joint count, and C-reactive protein.

RESULTS

Mean ± SD pain intensity was 5.32 ± 2.29 among women with RA, compared to 4.60 ± 2.23 among men with RA (adjusted difference 0.83 [95% confidence interval (95% CI) 0.14, 1.53]). Women with RA had lower pressure pain detection thresholds at the trapezius (adjusted difference -1.22 [95% CI -1.73, -0.72]), wrist (adjusted difference -0.57 [95% CI -1.07, -0.06]), and knee (adjusted difference -1.10 [95% CI -2.00, -0.21]). No statistically significant differences in pain interference, temporal summation, and conditioned pain modulation were observed.

CONCLUSION

Women reported higher pain intensity and lower pressure pain detection thresholds (higher pain sensitivity) than men. However, pain interference, temporal summation, and conditioned pain modulation did not differ between men and women.

Osteoporosis-related fractures in men and women with established and early rheumatoid arthritis: predictors and risk compared with the general population

OBJECTIVES

To study the risk of osteoporosis-related fractures in a community-based sample of men and women with rheumatoid arthritis (RA) overall, as well as early (< 1 year of disease duration, follow-up time maximum 10 years) and established (RA diagnosis since ≥ 5 years on July 1, 1997) RA, compared with the general population. To study potential risk factors for fractures in patients with RA from baseline questionnaire data.

METHODS

A community-based cohort of patients with RA (n = 1928) was studied and compared to matched general population controls. Information on osteoporosis-related fractures (hip, proximal upper arm, distal forearm and vertebral fractures) during the period July 1, 1997 to December 31, 2017 was obtained by linkage to the Swedish National Inpatient Register and the Cause of Death Register. The incidence of fractures was estimated in patients and controls. Cox regression models were used to assess the relation between RA and the risk of fractures and to assess potential predictors of fractures in RA patients. Analyses were stratified by sex, and performed in all patients with RA, and in subsets with early and established RA.

RESULTS

The overall incidence of osteoporosis-related fractures in the RA cohort was 10.6 per 1000 person-years (95% CI 9.31; 12.0). There was an increased risk of fractures overall in both men (hazard ratio (HR) 1.55, 95% CI 1.03; 2.34) and women (HR 1.52; 95% CI 1.27; 1.83) with RA compared to controls, with significantly increased risk also in the hip. No increased risk of osteoporosis-related fractures overall was seen in patients with early RA (HR 1.01, 95% CI 0.69; 1.49). Higher age, longer duration of RA, higher HAQ scores and higher scores in the visual analogue scale for global health were predictors of fractures.

CONCLUSION

Both men and women with RA were at increased risk of osteoporosis-related fractures. Patients with early RA did not have significantly increased risk during the first 10 years of disease in this study.

Influence of frailty on patient global assessment in rheumatoid arthritis

AIM

Patient Global Assessment (PtGA; range 0-10 cm) is an important indicator of clinical outcomes, including physical function, in self-assessment of patients with rheumatoid arthritis (RA). Frailty is a concept that encompasses not only physical, but also mental, psychological and social vulnerability. This study aimed to investigate the influence of frailty on PtGA in patients with RA.

METHODS

Among 581 patients with RA who completed a questionnaire survey on frailty between June and August 2020, 559 who completed the Kihon Checklist (KCL; a 25-item questionnaire with seven domains) were included. The proportion of patients with PtGA ≤1 was compared between the frailty (KCL score ≥8), pre-frailty (KCL score 4-7) and robust (KCL score 0-3) groups. Factors associated with PtGA ≤1 were examined using multivariate logistic regression models.

RESULTS

Of the 559 patients, 221 (39.5%) had frailty. The proportion of patients with PtGA ≤1 was significantly lower in the frailty group (33.9%) than in the robust (65.4%, P < 0.001) and pre-frailty (55.7%, P < 0.001) groups. Multivariate analysis revealed that frailty (vs robust, OR 0.37, 95% CI 0.22-0.69), as well as disease duration and tender joint count, were factors independently associated with PtGA ≤1. When each domain of the KCL was examined, activities of daily living, physical strength, isolation and depressive mood were factors associated with PtGA ≤1.

CONCLUSION

Frailty affects PtGA in patients with RA. As frailty impacts the physical, mental and social vulnerability aspects of PtGA, a multifaceted approach, including inflammation suppression, is required to improve PtGA in patients with RA. Geriatr Gerontol Int 2022; 22: 399-404.

Responses to Ixekizumab in Male and Female Patients with Psoriatic Arthritis: Results from Two Randomized, Phase 3 Clinical Trials

Introduction

Differences in psoriatic arthritis (PsA) treatment response between sexes for ixekizumab, an interleukin-17A antagonist, are largely unexplored. This analysis used data from randomized clinical trials (RCTs) evaluating ixekizumab to study differences in treatment response between male and female patients with PsA.

Methods

We used pooled data from patients enrolled in SPIRIT-P1 and SPIRIT-P2 (NCT01695239 and NCT02349295, respectively), phase 3 RCTs evaluating ixekizumab every 4 and 2 weeks in patients with active PsA. Subgroups of patients were defined by sex (male, female). Efficacy was measured by the proportion of male and female patients achieving American College of Rheumatology 20%/50%/70% improvement criteria (ACR20/50/70), minimal disease activity or very low disease activity (MDA/VLDA), and Disease Activity Index for Psoriatic Arthritis (DAPSA) scores representing low disease activity (LDA) or remission through week 156. Changes from baseline in components of the above measures were also assessed through week 156.

Results

Compared to male patients at baseline, female patients were older, had higher body mass index and lower C-reactive protein levels, and had worse tender joint count, Health Assessment Questionnaire Disability Index, and Leeds Enthesitis Index scores. Through week 156, female patients in all treatment arms had lower response rates than male patients in all analyzed composite measures (ACR20/50/70; MDA/VLDA; DAPSA LDA/remission), with significant differences observed at multiple timepoints in both ixekizumab treatment arms. Female patients also had smaller numeric changes from baseline in the composite measures’ individual components.

Conclusion

Compared to female patients, male patients had greater response rates in ACR20/50/70, MDA/VLDA, and DAPSA LDA/remission and numerically larger improvements in these measures’ individual components, although clinical significance is unclear. Continued efforts to understand sex differences in treatment response may provide insights that can help optimize clinical decision making.

Trial registration

ClinicalTrials.gov identifiers, NCT01695239 and NCT02349295.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40744-022-00445-w.

Predictors of unacceptable pain with and without low inflammation over 5 years in early rheumatoid arthritis-an inception cohort study

Objectives

Pain is a major symptom in patients with rheumatoid arthritis (RA). In early RA, pain is usually due to synovitis, but can also persist despite effective anti-inflammatory treatment. The objective of this study was to investigate the pain course over time and predictors of unacceptable pain and unacceptable pain with low inflammation, in patients with early RA.

Methods

An inception cohort of 232 patients with early RA, recruited in 1995–2005, was followed in a structured programme for 5 years. Pain was assessed using a visual analogue scale (VAS; 0–100). Unacceptable pain was defined as VAS pain > 40 based on the patient acceptable symptom state (PASS) and low inflammation as CRP < 10 mg/l. Baseline predictors of unacceptable pain were evaluated using logistic regression analysis.

Results

Pain improved significantly during the first 6 months, but then remained basically unchanged. Thirty-four per cent of the patients had unacceptable pain 5 years after inclusion. Baseline predictors of unacceptable pain after 5 years were lower swollen joint counts [odds ratio (OR) 0.71 per standard deviation (95% confidence interval (CI) 0.51–0.99)] and higher VAS for pain and global assessment of disease activity. Unacceptable pain with low inflammation after 5 years was negatively associated with anti-CCP antibodies [OR 0.50 (95% CI 0.22–0.98)].

Conclusion

Over one third of the patients had unacceptable pain 5 years after inclusion. Lower swollen joint count was associated with unacceptable pain at 5 years. The results may be explained by the positive effects of treatment on pain related to inflammation. Non-inflammatory long-lasting pain appears to be a greater problem in anti-CCP-negative patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02550-7.

Sex differences in clinical characteristics and their influence on clinical outcomes in an observational cohort of patients with rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is more prevalent in women, but sex differences remain incompletely understood. This study aimed to elucidate sex differences in clinical characteristics and their potential impact on clinical outcomes in a large Korean cohort of patients with RA.

METHODS

In total, 5376 RA patients from the KORean Observational study Network for Arthritis (KORONA) database were examined at baseline and for 3 consecutive years using the disease activity score 28 (DAS28), health assessment questionnaire (HAQ), and patient-reported outcomes (PROs). Within a subgroup with active disease (DAS28≥3.2) at baseline, sex impacts on clinical outcome during follow-up were analyzed using generalized estimating equation (GEE) models. The factors related to achieving clinical remission were analyzed using Cox-proportional hazard regression.

RESULTS

At baseline, women (n=4574) were younger and had more erosive disease and longer disease duration than men (n=802) with higher scores in DAS28, HAQ, and PROs. The prevalence of interstitial lung disease, cardiovascular disease, and diabetes in men was higher than that of women. In a RA subgroup with active disease at baseline, GEE analyses demonstrated that women RA significantly influenced the rate of change of DAS28 over time. In that group, men are associated with achieving DAS28 sustained remission and point remission.

CONCLUSIONS

Women with RA in Korea report higher levels of disease activity and PROs compared to men, whereas most comorbidities were more prevalent in men. The longitudinal change in disease activity and the rate of achieving clinical remission were found to be worse in women with RA.

Outcome after acute Achilles tendon rupture is not negatively affected by female sex and age over 65 years

PURPOSE

Studies suggest that women have worse treatment outcome than men after acute Achilles tendon rupture (ATR). The aim of this study was to investigate if sex and age affect treatment outcome after ATR.

METHODS

The study was performed as a registry study in the Danish Achilles tendon Database. The primary outcome was change in the Achilles tendon Total Rupture Score (ATRS) from baseline to 4 months, 1 year and 2 years follow-up. Variables of interest were sex and age group (< 40 years, 40-65 years and > 65 years).

RESULTS

Data were collected from April 2012 to March 2018. Five-hundred and sixteen patients (416 men, 100 women) were included in the study population. At baseline, women scored 4.3 points lower in ATRS compared to men. No statistically significant difference between the sexes regarding change in ATRS were found. Women scored statistically significantly less in absolute ATRS at 1 year follow-up (mean difference 9.4; 95% CI 3.8, 14.9; P = 0.03). Patients older than 65 years scored statistically significantly more in ATRS change compared to patients between 40-65 years (mean difference 12.8; 95% CI 6.1-19.5; P < 0.001).

CONCLUSION

This study did not show a statistically significant or clinically relevant difference between the sexes in ATRS change from baseline to follow-up. The mean difference in ATRS change between patients older than 65 years and patients between 40-65 years was clinically relevant with better outcome for patients older than 65 years. When comparing ATRS between groups with an unequal sex distribution, the findings of a baseline difference and a difference in absolute ATRS at 1 year follow-up between the sexes, advocate for reporting of sex-specific data or for use of change in ATRS from baseline to follow-up instead of absolute ATRS.

LEVEL OF EVIDENCE

Level III.

Fear of movement and (re)injury is associated with condition specific outcomes and health-related quality of life in women with patellofemoral pain

OBJECTIVES

Investigate the association of fear of movement and (re)injury with clinical outcomes in women with patellofemoral pain (PFP).

METHODS

This cross-sectional study included 92 women with PFP who completed the TAMPA scale for kinesiophobia. The TAMPA score and its two subscales - activity avoidance and somatic focus were correlated with BMI, physical activity level, pain catastrophizing scale, health-related quality of life, pain sensitivity via pressure pain threshold, self-reported disability, and worst knee pain in last month.

RESULTS

Greater fear of movement and (re)injury, activity avoidance, and somatic focus were correlated with lower local pain sensitivity (rho = -0.29 to -0.55), lower health-related quality of life (rho = -0.38 to -0.42), greater pain catastrophizing (rho = 0.41 to 0.47), and greater self-reported disability (rho = -0.31 to -0.52). Greater fear of movement and (re)injury and activity avoidance were correlated with adjacent and remote pain sensitivity (rho = -0.24 to -0.39). Greater fear of movement and (re)injury and somatic focus were correlated with greater worst knee pain in last month (rho = 0.21 to 0.32). Fear of movement and (re)injury predicted pain measures, disability, and health-related quality of life (p ≤ 0.010).

CONCLUSION

The relationship of greater fear of movement and (re)injury with greater disability, pain catastrophizing, pain sensitization, and poorer health-related quality of life highlights the potential importance of considering this psychological feature of PFP during assessment and management.

Understanding differences between men and women with axial spondyloarthritis

Axial spondyloarthritis (axSpA) is a chronic inflammatory immune-mediated disease resulting in inflammatory low back pain and other inflammatory manifestations in peripheral joints and entheses. AxSpA encompasses both ankylosing spondylitis (AS), in which patients present with definitive sacroiliitis visible on radiographic imaging, as well as nonradiographic axSpA (nr-axSpA), in which such changes may not be discernable. Emerging evidence suggests that women and men experience axSpA differently. Although the prevalence of AS is approximately 2- to 3- fold higher in men than in women, nr-axSpA occurs with roughly equal frequency in women and men. The goal of this review is to increase awareness of sex differences in axSpA by exploring the distinct manifestations of disease and disease characteristics in women, the overall clinical burden, recommendations for diagnosis, and potential treatment options. We summarize and contextualize the results of recent studies that illuminate sex differences in nr-axSpA and AS, including differences in disease manifestation and progression. It is important that sex differences in axSpA are understood and considered when diagnosing and treating the spectrum of axSpA, including AS and nr-axSpA.

Co-Morbidities and Sex Differences in Long-Term Quality-of-Life Outcomes among Patients with and without Diabetes after Total Knee Replacement: Five-Year Data from Registry Study

Improved understanding of quality-of-life (QoL) outcomes can provide valuable information on intervention effectiveness and guide better patient care. The aim of this study was to examine whether QoL trajectories differ between patients with and without diabetes and identify to what extent patient characteristics are related to poor QoL outcomes after total joint replacement (TKR). Multilevel modelling was used to analyse long-term QoL patterns of patients undergoing TKR between 2006 and 2011. Patient-reported QoL at baseline and up to 5 years post-surgery were included. Of the 1553 TKR patients, one-fifth (n = 319) had diabetes. Despite there being no significant differences in QoL at baseline, patients with diabetes consistently reported lower QoL (on average by 0.028, p < 0.001) and did not improve to the same level as patients without the disease following surgery. Compared to males, females had significantly lower QoL (by 0.03, p < 0.001). Other baseline patient characteristics associated with important differences in QoL included presence of respiratory disease and mental health disorder. Patients with diabetes exhibit significantly poorer QoL compared to patients without diabetes, particularly among females. Knowledge of risk factors that impact on QoL can be useful for clinicians in identifying characteristics related to poor QoL outcomes and be used to guide patient-centered care.

Effects of Treatment with Adalimumab on Blood Lipid Levels and Atherosclerosis in Patients with Rheumatoid Arthritis

Background

Treatment with tumor necrosis factor inhibitors for rheumatoid arthritis has been associated with a decreased risk of cardiovascular disease in observational studies. There are conflicting data on the influence of tumor necrosis factor inhibitors on lipid levels.

Objectives

To evaluate the effect of treatment with adalimumab on blood lipid levels, lipoproteins, and atherosclerosis of the carotid artery.

Methods

Fourteen patients with active rheumatoid arthritis (11 women and 3 men; mean age 63.7 years; median disease duration 9.0 years; and 78% rheumatoid factor positive) were treated with adalimumab 40 mg subcutaneously every 2 weeks and followed for 3 months. The patients had not been treated with adalimumab previously and had not received other tumor necrosis factor inhibitors within the past 3 months or moderate/high dose corticosteroids within the past 2 weeks. The intima-media thickness of the common carotid artery was assessed using B mode ultrasonography. Triglycerides, total cholesterol, LDL cholesterol, and HDL cholesterol levels were analyzed in fresh fasting blood samples, whereas apolipoprotein B and apolipoprotein A1 (apoA1) levels were determined in thawed plasma samples using standard turbidimetric immunoassays.

Results

Total cholesterol (mean = 5.36 vs 5.96 mmol/L; P = 0.005), LDL cholesterol (mean = 3.33 vs 3.77 mmol/L; P = .005), HDL cholesterol (mean = 1.43 vs 1.55 mmol/L; P = 0.048), apolipoprotein B (mean = 1.04 vs 1.13 g/L; P = .012), and apoA1 (mean = 1.42 vs 1.58 g/L; P = 0.005) all increased, but there were no major changes in the LDL to HDL cholesterol ratio (median = 2.56 vs 2.35; P = 0.27) or the apolipoprotein B to apoA1 ratio (mean = 0.76 vs 0.74; P = 0.46). There was no change in triglyceride levels (P = 0.55). Disease activity decreased significantly from baseline to the 3-month evaluation (disease activity score based on 28 joints mean = 5.6 vs 4.1; P = 0.007). An increase in apoA1 correlated with decreases in the patient global assessment of disease severity (r = 0.79; P = 0.001) and C-reactive protein level (r = 0.74; P = 0.003). Changes in the apoliprotein B to apoA1 ratio correlated with changes in erythrocyte sedimentation rate (r = 0.54; P = 0.046). There was no major change in the common carotid artery intima-media thickness (mean = 0.78 vs 0.80 mm; P = 0.48).

Conclusions

Although these results suggest that control of inflammation could have a beneficial effect on the lipid profile through an increase in HDL cholesterol levels, the observed protective effect on cardiovascular disease events by tumor necrosis factor blockers is likely to be explained by other mechanisms than changes in lipid levels or short-term effects on atherosclerosis of the carotid artery.

Course of Grip Force Impairment in Patients With Early Rheumatoid Arthritis Over the First Five Years After Diagnosis

OBJECTIVE

Objective measures of function are important in rheumatoid arthritis (RA). The objective of this study was to investigate grip strength in patients with early RA.

METHODS

An inception cohort of 225 patients with early RA was followed in accordance with a structured protocol. Average and peak grip force values of the dominant hand (measured using a Grippit device [AB Detektor]) were evaluated and compared to expected age- and sex-specific reference values from the literature. Separate analyses were performed for those with limited self-reported disability (Health Assessment Questionnaire disability index [HAQ DI] score ≤0.5) and clinical remission (Disease Activity Score in 28 joints <2.6).

RESULTS

Baseline average grip force among RA patients was significantly lower than the corresponding expected value (mean 105N versus 266N; P < 0.001). Observed average and peak grip force values were significantly reduced compared to those expected in women as well as in men over time and at all time points. The average grip force improved significantly from inclusion to the 12-month visit (age-corrected mean change 34N [95% confidence interval 26-43]). At 5 years, the average grip force was still lower than that expected overall (mean 139N versus 244N; P < 0.001), and also among those with HAQ DI scores ≤0.5 and those in clinical remission.

CONCLUSION

Grip strength improved in early RA patients, particularly during the first year. However, it was still significantly impaired 5 years after diagnosis, even among those with limited self-reported disability and those in clinical remission. This suggests that further efforts to improve hand function are important in early RA.

Impact of Gender Disparities on Short-Term and Long-Term Patient Reported Outcomes and Satisfaction Measures After Elective Lumbar Spine Surgery: A Single Institutional Study of 384 Patients

BACKGROUND

There is a paucity of data determining the impact that gender disparities have on spine outcomes, particularly perception of health and satisfaction. The aim of this study was to determine whether there is a difference in 3-month and 1-year patient-reported outcomes and satisfaction after elective lumbar spine surgery.

METHODS

This was a retrospectively analyzed study from a maintained prospective database of 384 patients who underwent elective lumbar spine surgery. Patients were categorized by gender (men, n = 199; women, n = 185). Patient-reported outcome instruments (Oswestry disability index, visual analogue scale-back pain/leg pain, EuroQol visual analogue scale, and EuroQol 5 dimensions questionnaire) were completed before surgery, then at 3 and 12 months after surgery along with patient satisfaction measures.

RESULTS

Baseline patient demographics, comorbidities, and operative variables were similar between both cohorts. The female cohort had a slightly longer hospital stay than male cohort (P = 0.007). Baseline patient-reported outcome measures were different between both cohorts, with female patients having more Oswestry disability index (23.8 vs. 20.4; P ≤ 0.0001) and visual analogue scale-back pain (7.2 vs. 6.2; P = 0.0004), and a lower EuroQol 5 dimensions questionnaire (0.34 vs. 0.49; P = 0.0001) compared with the male cohort. At 1-year follow-up, the male cohort had a significantly more mean change in visual analogue scale-leg pain (-3.9 vs. -2.8; P = 0.04) and trended to have more mean change in visual analogue scale-back pain (-3.4 vs. -2.5; P = 0.06) and EuroQol visual analogue scale (8.6 vs. 3.4; P = 0.054) scores compared with the female cohort. At 1-year a significantly more portion in the male cohort found that surgery met their expectations compared with the female cohort (65.0% vs. 49.5%; P = 0.02).

CONCLUSIONS

Our study suggests that there may be differences in perception of health, pain, and disability between men and women at baseline, short-term and long-term follow-up that may influence overall patient satisfaction.

Severe Extraarticular Manifestations in a Community-based Cohort of Patients with Rheumatoid Arthritis: Risk Factors and Incidence in Relation to Treatment with Tumor Necrosis Factor Inhibitors

Objective.

The aims of this study were to evaluate whether treatment with tumor necrosis factor (TNF) inhibitors in patients with rheumatoid arthritis (RA) affects the risk of developing severe extraarticular rheumatoid arthritis (ExRA) manifestations and to investigate potential predictors for developing ExRA.

Methods.

A dynamic community-based cohort of patients with RA was studied (n = 1977). Clinical records were reviewed and cases of severe ExRA were identified. Information on exposure to TNF inhibitors was obtained from a regional register. Exposure to TNF inhibitors was analyzed in a time-dependent fashion and the incidence of severe ExRA in exposed patients was compared with the incidence in unexposed patients. Cox regression models were used to assess potential predictors of severe ExRA.

Results.

During treatment with TNF inhibitors, there were 17 patients with new onset of severe ExRA in 2400 person-years at risk (PY; 0.71/100 PY, 95% CI 0.41–1.13) compared with 104 in 15,599 PY (0.67/100 PY, 95% CI 0.54–0.81) in patients without TNF inhibitors. This corresponded to an incidence rate ratio of 1.06 (95% CI 0.60–1.78). The age- and sex-adjusted HR for ExRA in anti-TNF–treated patients was 1.21 (95% CI 1.02–1.43), with similar findings in models adjusted for time-dependent Health Assessment Questionnaire and propensity for anti-TNF treatment. Male sex, positive rheumatoid factor (RF), long disease duration, and greater disability were predictors for ExRA.

Conclusion.

This study suggests that patients treated with TNF inhibitors are at a slightly increased risk of developing severe ExRA. RF-positive patients with disabling disease of long duration were more likely to develop severe ExRA.

Back pain and health status in patients with clinically diagnosed ankylosing spondylitis, psoriatic arthritis and other spondyloarthritis: a cross-sectional population-based study

Background

In the broader spectrum of back pain, inflammatory back pain (IBP) is a symptom that may indicate axial spondyloarthritis (SpA). The objectives of this study were to determine the frequency of current IBP, as a hallmark sign of possible axial SpA, in patients with ankylosing spondylitis (AS), psoriatic arthritis (PsA) and other SpA and to compare self-reported health between the groups with current IBP.

Methods

Five-thousand seven hundred seventy one patients identified in the regional healthcare register of the most southern county of Sweden, diagnosed at least once by a physician (based on ICD-codes) with any type of SpA in 2003–2007, were sent a postal survey in 2009. Patients with current IBP were identified, based on self-reported back pain ≥3 months in the preceding year and fulfilling the Berlin criteria for IBP. The frequencies of IBP in AS, PsA and other SpA (including the remaining subgroups of SpA) were determined, and the groups were compared with regard to patient reported outcome measures (PROMs).

Results

The frequency and proportion of patients with current IBP in AS, PsA and other SpA were 319 (43 %), 409 (31 %) and 282 (39 %) respectively, within the responders to the survey (N = 2785). The proportion was statistically higher in AS, compared to PsA (p < 0.001), but not for AS compared to other SpA (p = 0.112). PsA and other SpA, with current IBP, had similar (BASFI, EQ-5D, patients global assessment, fatigue, spinal pain) or worse (BASDAI) PROMs, compared to AS with current IBP. PsA with current IBP received pharmacological, anti-rheumatic, treatment more frequently than AS with current IBP, while AS and other SpA received treatment to a similar degree.

Conclusion

The proportion of patients with current IBP was substantial in all three groups and health reports in the non-AS groups were similar or worse compared to the AS group supporting the severity of IBP in these non-AS SpA groups. These findings may indicate a room for improvement concerning detection of axial disease within different subtypes of non-AS SpA, and possibly also for treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-0960-8) contains supplementary material, which is available to authorized users.