Pain Features And Their Relationships With Disease Activity And Functional Status In Axial Spondyloarthritis Patients

BackgroundPain is one of the major symptoms in patients with axial spondyloarthritis(axSpA)and the accurate assessment of pain could give clearer insights regarding disease activity and functional status,which helps guide clinical treatment and outcome evaluation.Inflammatory back pain(IBP)is the predominant symptom of axSpA.Researches indicate that pain in axSpA patients includes neuropathic pain(NP)component.However,the characteristics of IBP or NP and its relationship with disease activity and functional status have not been reported so far.Objectives1.To assess the incidence and related factors of IBP or NP;2.To identify pain intensity,interference,quality,and catastrophizing of IBP or NP;3.To clarify disease activity and functional status associated with IBP or NP in patients with axSpA.Methods1.ParticipantsA convenience sample of 132 patients was recruited from the Department of Rheumatology and Immunology in a university-affiliated hospital in Guangzhou,China,from June 2016 to April 2017.2.Instruments2.1 Pain assessmentThe Berlin criteriaPatients were diagnosed of IBP by the Berlin Criteria.IBP is considered in the presence of 2 of 4 features.The Douleur Neuropathique 4 questionnaire(DN4)The DN4 is a 10-item questionnaire.Subjects with a total DN4 score ≥4 were considered as NP.The Brief Pain Inventory(BPI)The Brief Pain Inventory(BPI)includes pain intensity and pain interference on a 0-10 numeric rating scale(NRS).Patients were also asked how much relief they have received provided by pain treatments or medications on a percentage scale(0-100%).The Short-Form McGill Pain Questionnaire(SF-MPQ)Descriptors 1-11 of the SF-MPQ represent the sensory dimension of pain experience and 12-15 represent the affective dimension.Each descriptor is ranked on an intensity scale of 0-4.Pain Catastrophizing Scale(PCS)The PCS is a 13-item questionnaire.Subjects with a total PCS score>30 are considered more likely to develop catastrophic pain.2.2 Disease activity and functional statusThe Bath Ankylosing Spondylitis Disease Activity Index(BASDAI)was developed to assess disease activity in patients with a total score of 0-10.The higher the total scores,the higher the disease activity.The Bath Ankylosing Spondylitis Functional Index(BASFI)was to evaluated physical functioning in patients with ankylosing spondylitis with a total score of 0-10.The higher the total scores,the worse functional status.The Bath Ankylosing Spondylitis Metrology Index(BASMI)was used to quantify the mobility of the axial skeleton with a total score of 0-10.The higher the total scores,the worse spinal mobility.3.ProceduresPatients completed questionnaires which including pain assessment,disease activity and fuctional status.The DN4 and BASMI examinations were conducted by the investigator.Demographic and clinical information including age,gender,height and weight for the calculation of body mass index(BMI),cigarette smoking,alcohol drinking,disease duration,recent laboratory examinations(C-reactive protein and erythrocyte sediment rate),and anti-inflammatory drugs were also collected.Results1.37.9%axSpA patients had IBP and 16.7%NP.Patients had a BMI≥24 kg/meters2 were significantly more frequent in patients with IBP than those without(P=0.007).The percentage of patients who received TNFi or NSAIDs was significantly higher in non-IBP than IBP patients.The NP patients had more smoking(P=0.008)and alcohol drinking(P=0.001)than non-NP patients.2.Patients with IBP experienced mild to moderate pain and interference.Scores of pain intensity and interference,BASDAI,and BASFI were significantly higher in patients with IBP than those without(P<0.05).Patients with IBP had a higher score of"cramping" in pain sensory descriptors(P=0.021)and "tiring-exhausting" in pain affective descriptors(P=0.041).Patients with NP experienced moderate pain and interference.Scores of pain intensity and interference,BASDAI,BASFI and BASMI were significantly higher in patients with NP than those without(P<0.05)."Throbbing"(P=0.004),"stabbing"(P=0.022),"sharp"(P=0.014),and "hot-burning"(P=0.002)in pain sensory descriptors scored higher in patients with NP than those without.Significant differences were not observed between groups regarding C-reactive protein,erythrocyte sediment rate and pain catastrophizing.3.There was a significant correlation between IBP and disease activity,and NP was related to functional limitation(P<0.05).ConclusionsPatients with IBP or NP have more severe pain intensity and interference,disease activity and functional limitation.The IBP is related to disease activity and has an impact on mood.The NP is associated with functional status and presented as spontaneous pain.Assessment of pain features of the patients could give more information about the disease activity and clinical outcomes.