Objective: To address the need for standardization of osteoarthritis (OA) phenotypes by examining the effect of heterogeneity among symptomatic (SOA) and radiographic osteoarthritis (ROA)... Show moreObjective: To address the need for standardization of osteoarthritis (OA) phenotypes by examining the effect of heterogeneity among symptomatic (SOA) and radiographic osteoarthritis (ROA) phenotypes. Methods: Descriptions of OA phenotypes of the 28 studies involved in the TREAT-OA consortium were collected. We investigated whether different OA definitions result in different association results by creating various hip OA definitions in one large population based cohort (the Rotterdam Study I (RSI)) and testing those for association with gender, age and body mass index using one-way ANOVA. For ROA, we standardized the hip-, knee- and hand ROA definitions and calculated prevalence's of ROA before and after standardization in nine cohort studies. This procedure could only be performed in cohort studies and standardization of SOA definitions was not feasible at this moment. Results: In this consortium, all studies with SOA phenotypes (knee, hip and hand) used a different definition and/or assessment of OA status. For knee-, hip- and hand ROA five, four and seven different definitions were used, respectively. Different hip ROA definitions do lead to different association results. For example, we showed in the RSI that hip OA defined as "at least definite joint space narrowing (JSN) and one definite osteophyte" was not associated with gender (P=0.22), but defined as "at least one definite osteophyte" was significantly associated with gender (P=3 x 10(-9)). Therefore, a standardization process was undertaken for ROA definitions. Before standardization a wide range of ROA prevalence's was observed in the nine cohorts studied. After standardization the range in prevalence of knee- and hip ROA was small. Conclusion: Phenotype definitions influence the prevalence of OA and association with clinical variables. ROA phenotypes within the TREAT-OA consortium were standardized to reduce heterogeneity and improve power in future genetics studies. (C) 2010 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved. Show less
Meulenbelt, I.; Bos, S.D.; Chapman, K.; Breggen, R. van der; Houwing-Duistermaat, J.J.; Kremer, D.; ... ; Slagboom, E. 2011
Objective To study whether common genetic variants of the genes involved in the complex regulatory mechanism determining the intracellular bio-availability of T3 influence osteoarthritis onset.... Show moreObjective To study whether common genetic variants of the genes involved in the complex regulatory mechanism determining the intracellular bio-availability of T3 influence osteoarthritis onset. Methods In total 17 genetic variants within the genes encoding WD40-repeat/SOCS-box protein 1, ubiquitin specific protease 33, thyroid hormone receptor alpha, deiodinase, iodothyronine, type III (DIO3) and Indian hedgehog were measured and associated with osteoarthritis in a meta-analyses in European populations from the UK, The Netherlands, Greece and Spain containing a total of 3252 osteoarthritis cases and 2132 controls. Results The minor allele of the DIO3 variant rs945006 showed suggestive evidence for protective association in the overall meta-analyses, which was supported by individual osteoarthritis studies and osteoarthritis subtypes. The association appeared most significant in cases with knee and/or hip with an allelic OR of 0.81 (95% CI 0.70 to 0.930) with a nominal p value of 0.004 and a permutation-based corrected p value for multiple testing of 0.039. Conclusion The findings suggest that the DIO3 gene modulates osteoarthritis disease risk; however, additional studies are necessary to replicate our findings. To elucidate the molecular mechanisms focus should be on the local adaptation to T3 availability either during the endochondral ossification process or during ageing of the articular cartilage. Show less
