Objectives It is currently impossible to identify which patients with knee complaints presenting to the general practitioner will develop knee osteoarthritis (OA) pathology at a later stage. This study examines the determinants for developing OA pathology on x-ray in patients with knee complaints but no radiological OA at baseline in the painful knee.
Methods Data from the prospective Rotterdam cohort study (including subjects aged ≥55 years) were used. Analysis was performed on 623 subjects with knee complaints at baseline and their data at 6-year follow-up (T1; n=607) and at 11-year follow-up (T2; n=457). At baseline, none had radiological OA (rOA=Kellgren and Lawrence (KL) grade ≥2) in the painful joint. At follow-up, predictors for rOA were determined using multivariate ordinal logistic regression analysis.
Results At T1, 8.5% of the group had developed knee rOA and, by T2, this had increased to 23%. Determinants remaining significant in the multivariate analysis were female gender (OR 1.95, 95% CI 1.15 to 3.36), other joint complaints (OR 2.22, 95% CI 1.12 to 4.35) and KL grade 1 at baseline in the painful knee joint (OR 7.14, 95% CI 4.55 to 11.1). All outcomes are adjusted for all included determinants.
Conclusion The best predictors of development of knee rOA are a combination of female gender, other joint complaints and KL grade 1 in the painful joint. KL grade 1 in combination with knee pain should be considered as early OA in patient management.
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Contributors All authors contributed to the final manuscript. In addition, BMdK and DS collected data. BMdK, SW and SMAB-Z performed statistical analysis and data interpretation. BMdK wrote the manuscript. BWK and SMAB-Z critically revised the article for important intellectual content. AH conceived the original Rotterdam Study. SMAB-Z conceived the study, and participated in its design and coordination, helped to draft the manuscript and supervised the whole study. BMdK had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. All authors read and approved the final manuscript.
Funding This study was funded by a grant from The Netherlands Organisation for Scientific Research (NWO Vidi scheme, 91766350). The Rotterdam Study is funded by the Erasmus Medical Center and Erasmus University Rotterdam, the Netherlands Organisation for Health Research and Development (ZonMw), the Research Institute for Diseases in the Elderly (RIDE), the Ministry of Education, Culture and Science, the Ministry for Health, Welfare and Sports, the European Commission (DG XII) and the municipality of Rotterdam.
Competing interests None.
Patient consent Obtained.
Ethics approval Ethics approval was obtained from the medical ethics committee of the Erasmus University Medical Center.
Provenance and peer review Not commissioned; externally peer reviewed.