Development of a prognostic score for work disability in Romanian patients with ankylosing spondylitis.
PURPOSE
To develop a prognostic score for predicting work disability (WD) in patients with ankylosing spondylitis (AS) as strong indicator for poor vocational rehabilitation.


METHOD
A cross-sectional study was performed in a group of 170 patients with AS, 120 work disabled and 50 still employed. The variables strongly associated with WD were quantified (scored 0-30) - abnormalities of: anterior-posterior radiograph of pelvis, lateral cervical spine radiograph and lung function tests, certain work factors (occupation, physical strain and microclimate), Bath Ankylosing Spondylitis Mobility Index and Bath Ankylosing Spondylitis Functional Index tests.


RESULTS
The eight-item score identifies WD with sensitivity of 91.7% and specificity of 85.7%. The scaling properties were fulfilled: internal consistency - Chronbach's alpha 0.73; reliability - intraclass correlation coefficient 0.73; redundancy weak-moderate, with coefficients ranging from 0.032 to 0.797; the discriminative capacity by the significant variations of the score according to the statute (employed or work disabled) and the degree of WD.


CONCLUSIONS
The score is a reliable method for assessing the WD risk in patients with AS. It allows a complex evaluation by performing minimal investigations and it is easy to perform.


IMPLICATIONS FOR REHABILITATION
Work disability is an important outcome in AS, determined by numerous variables but highly dependent on the national characteristics of economy, social security and healthcare system. The prognostic score for work disability in AS not only contains medical but also socio-demographic and work-related factors and is expected to be a useful tool for specialists to guide the tertiary prevention-oriented rehabilitation measures. Our study suggests the prognostic score to be comprehensive, useful and a reliable method to assess the risk of work disability in AS.