Abstract
ObjectivesTo validate and optimize a referral rule to identify primary care patients with chronic low back pain (CLBP) suspected for axial spondyloarthritis (axSpA).DesignCross-sectional study with data from 19 Dutch primary care practices for development and 38 for validation.ParticipantsPrimary care patients aged 18-45 years with CLBP existing more than three months and onset of back pain started before the age of 45 years.Main OutcomeThe number of axSpA patients according to the ASAS criteria.MethodsThe referral rule (CaFaSpA referral rule) was developed using 364 CLBP patients from 19 primary care practices and contains four easy to use variables; inflammatory back pain, good response to nonsteriodal anti-inflammatory drugs, family history of spondyloarthritis and a back pain duration longer than five years. This referral rule is positive when at least two variables are present. Validation of the CaFaSpA rule was accomplished in 579 primary care CLBP patients from 38 practices from other areas. Performance of the referral rule was assessed by c-statistic and calibration plot. To fit the final referral rule the development and validation datasets were pooled leading to a total study population of 943 primary care participants.ResultsThe referral rule was validated in 579 patients (41% male, mean age 36 (sd7.0). The percentage of identified axSpA patients was 16% (n=95). External validation resulted in satisfactory calibration and reasonable discriminative ability (c-statistics 0.70 [95% CI, 0.64-0.75]). In the pooled dataset sensitivity and specificity of the referral rule were 75% and 58%.ConclusionsThe CaFaSpA referral rule for axSpA consists of four easy to use predictors for primary care physicians and has a good predictive value in this validation study. The referral rule has the potential to be a screening tool for primary care by identifying CLBP patients suspected for axSpA.
Highlights
Axial spondyloarthritis is relative new term in the field of rheumatology
External validation resulted in satisfactory calibration and reasonable discriminative ability (c-statistics 0.70 [95% CI, 0.64-0.75])
There is a delay of 4–9 years between the first chronic low back pain (CLBP) symptoms and the final diagnosis of axial spondyloarthritis (axSpA). [6, 7] This delay can be explained by the difficulty for primary care physicians to recognize an axSpA patient in the large amount of CLBP patients seen in primary care
Summary
Axial spondyloarthritis (axSpA) is relative new term in the field of rheumatology. It is a chronic inflammatory joint disease, that is potentially disabling and characterized by chronic low back pain (CLBP). [1] AxSpA is associated with increased morbidity, mortality, high health care costs and reduced work productivity. [2, 3] Quality of life and work participation can be improvement with effective treatment; non-steroidal anti-inflammatory drugs (NSAIDs) and biologicals.[4]. Axial spondyloarthritis (axSpA) is relative new term in the field of rheumatology It is a chronic inflammatory joint disease, that is potentially disabling and characterized by chronic low back pain (CLBP). Most of the published referral rules were not easy to use, costly, or developed in secondary care patients. This pre-selection of patients makes it hard to implement these referral strategies in primary care practice. [18] In 2014 we published the CaFaSpA referral rule, a referral strategy for axSpA developed in primary care patients with CLBP and applicable for primary care physicians. [7] In this study we want to externally validate and optimize the performance of this CaFaSpA referral rule in another, independent population of young primary care CLBP patients Most published referral strategies are merely based on development studies so no external validation took place, an important step for deriving a clinical useful referral strategy. [18] In 2014 we published the CaFaSpA referral rule, a referral strategy for axSpA developed in primary care patients with CLBP and applicable for primary care physicians. [7] In this study we want to externally validate and optimize the performance of this CaFaSpA referral rule in another, independent population of young primary care CLBP patients
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