The Exploration And Preliminary ’Validation Of A New Scoring Method For Hip Joint Involvement In Ankylosing Spondylitis

Objective:To describe the structural progression of hip joint in ankylosing spondylitis(AS)in a more efficient way,a new scoring method were developed and its reliability,clinical feasibility and discriminability were examined.Methods:According to the radiological characteristics of hip involvement in AS and prior methods,a new scoring method comprised of erosion,sclerosis and joint space narrowing were established,by which pelvis anterior-posterior plains acquired from baseline and follow-up were scored by two observers(well-trained physicians)independently and blindly.The reliability of the new scoring method were assessed by inter-and intra-observer reliability,calculated by intra-class correlation coefficient(ICC),its clinical feasibility were assessed by the mean time acquired to score a plain(two hips),its ability to detect the change of radiological progression were assessed by the comparison of score differences between baseline and different follow-up,which were analyzed by paired-t test or nonparametric tests.Analysis of Variance(ANOVA)or nonparametric tests were utilized for the comparison of means of quantitative variables among the three groups,while chi-square test for rates of categorical variables.Smallest detectable change(SDC)were calculated as well to distinguish the real score change from random error.Results:Patients fell into three groups by follow-up duration with 1-2 years,3-4 years or over 5 years,no statistically significant differences existed in baseline’s demographic data and suspected risk factors among the three groups(P>0.05).Intra-observer reliability was good(0.84 and 0.89),as well as the inter-observer reliability(0.72),the mean time needed to score was 33±10 seconds.Score changes were not statistically significant in the groups with follow-up duration of 1～2 and 3～4 years,the baseline/final scores assessed by the two observers for the duration of 1-2 years were 6.76±2.62/6.89±2.93(t=0.48,P>0.05)and 6.21 ±2.84/6.17±2.89(t=0.22,P>0.05)respectively,as well 6.53±3.17/7.03±2.46(t=1.36,P>0.05)and 5.97±2.88/6.78±3.57(Z=-1.82,P>0.05)for 3-4 years.However,in the group of over 5 years,baseline/final scores assessed by the two observers were 6.00±2.67/7.50±3.70(t=2.86,P<0.01)and 5.55±2.11/7.14±3.62(Z=-2.99,P<0.01)respectively,both changes were of statistical significance(P<0.01).From the perspective of collectivity,score changes were only of significant value in the interval of over 5 years from the observers,whereas in the individual level,there existed considerable percentage of real score change in all groups from the observers—both aggravating and alleviative.Conclusion:A new scoring method for structural damage of hip involvement in AS were developed,which were of acceptable reliability and clinical feasibility,as well considerable sensitivity to radiological change of hip involvement in AS,and it is worth further validation in larger populations.