IntroductionPulmonary involvement is a known manifestation in patients with ankylosing spondylitis (AS). However, previous studies have been based on small samples and the reported prevalence and associations with typical clinical features vary. The purpose of this study was to compare pulmonary function (PF) in patients with AS and population controls, and to study associations between PF and disease related variables, cardio-respiratory fitness and demographic variables in patients with AS.MethodsIn a cross-sectional controlled study, 147 AS patients and 121 controls underwent examinations, including demographic variables, laboratory (C-reactive protein (CRP), erythrocyte sedimentation rate (ESR)) and clinical measures (disease activity (AS disease activity score, ASDAS), physical function (Bath ankylosing spondylitis functional index, BASFI), spinal mobility (Bath ankylosing spondylitis metrology index, BASMI), chest expansion, cardio-respiratory fitness (peak oxygen uptake, VO2peak) and pulmonary function test (PFT) (spirometry)). Cumulative probability plots were used to visualize associations between the ASDAS and BASMI scores and the corresponding forced vital capacity (FVC%, percentage of predicted value controlled for the influence of confounding factors) score for each patient. Univariate ANCOVAs were performed to explore group differences in PF adjusting for relevant variables, and a multiple regression model was used to estimate the explanatory power of independent variables (demographic, disease related, VO2peak) on restrictive ventilatory impairment (FVC%).ResultsAS patients showed significantly lower PF values compared with controls, and significantly more patients were categorized with restrictive pattern (18% vs. 0%, P < 0.001). Cumulative probability plots showed significant associations between spinal mobility measures (BASMI) and FVC% for individual patients. BASMI, chest expansion and male gender contributed significantly and independently in a multiple regression model predicting the variation of FVC% in AS patients, whereas disease activity, physical function and VO2peak did not contribute significantly. The final model explained 45% of the variance in FVC% (P < 0.001).ConclusionsThis study showed significantly impaired pulmonary function in the AS patients compared to controls and reference data, and demonstrated a clear relationship between reduced spinal mobility and restrictive PF in AS patients. The results support the assumption of an association between musculoskeletal limitations and restrictive respiratory impairment in AS, emphasizing the importance of maintaining spinal flexibility in the management of the disease. Further, patients with severely reduced spinal mobility should be referred for pulmonary function examination and relevant follow-up treatment.

BackgroundComprehensive rehabilitation, involving health professionals from various disciplines, is widely used as an adjunct to pharmacological and surgical treatment in people with rheumatic diseases. However, the evidence for the clinical- and cost-effectiveness of such interventions is limited, and the majority of those who receive rehabilitation are back to their initial health status six to 12 months after discharge.Methods/designTo evaluate the goal attainment, health effects and cost-effectiveness of a new rehabilitation programme compared to current traditional rehabilitation programmes for people with rheumatic diseases, a stepped-wedge cluster randomized trial will be performed. Patients admitted for rehabilitation at six centres in the south-eastern part of Norway will be invited to participate. In the trial, six participating centres will switch from a control (current rehabilitation programme) to an intervention phase (the new rehabilitation programme) in a randomized order. Supported by recent research, the new programme will be a supplement to the existing programme at each centre, and will comprise four elements designed to enhance and support lifestyle changes introduced in the rehabilitation period: structured goal-planning, motivational interviewing, a self-help booklet and four follow-up telephone calls during the first five months following discharge. The primary outcome will be health-related quality of life and goal attainment, as measured by the Patient Generated Index directly before and after the rehabilitation stay, as well as after six and 12 months. Secondary outcomes will include self-reported pain, fatigue, a global assessment of disease activity and motivation for change (measured on 11-point numeric ratings scales), health-related quality of life as measured by the Short Form 36 Health Survey (SF-36) and utility assessed by the SF6D utility index.The main analysis will be on an intention to treat basis and will assess the clinical- and cost-effectiveness of the structured goal planning and tailored follow-up rehabilitation programme for patients with rheumatic diseases.DiscussionThe findings will constitute an important contribution to more cost-effective- and evidence-based rehabilitation services for people with rheumatic diseases.Trial registrationISRCTN91433175.

The add-on program enhanced the short-term effect of rehabilitation with respect to patient-specific HRQoL, but it did not prolong the effect as intended.