Pre-operative BMI as a predictor of patient reported outcomes of primary hip replacement surgery: a combined analysis of 4 prospective cohort studies

Abstract

s / Osteoarthritis and Cartilage 20 (2012) S54–S296 S152 study ,using the cell culturing technology, was to observe what different results would come out from the MTTassay of the ATDC5 cell proliferation, whick had been cultured with different concentration E2. Methods: The 17-bestradiol we use was ordered from Sigma co. and the ATDC5 cell line was form the Riken cell bank. We culture the ATDC5 24 hours in the media with different concentration 17-bestradiol, then we test the OD value of the different cells in MTT assay to assume the proliferation of the ATDC5. Results: After culturing 24 hours in the media with different concentration 17-bestradiol, the proliferation of the ATDC5 in different concentration 17-bestradiol were different significantly, the higher of the concentration, the higher of the proliferation, as follows: beside the 10-11M against 0 M, the 10-10,10-9,10-8 and 10-7 M have significant difference in stimulating the proliferation of ATDC5 against 0 M. between the different concentration groups, only 10-8 M has significant difference against 10-11,10-10 M. Conclusions: First, 17-bestradiol has stimulation on the proliferation of ATDC5. Second, 10-8 M concentration of 17-bestradiol has the strongest stimulating effect than the other concentration of 17-bestradiol. Clinical Aspects / Outcomes 302 PRE-OPERATIVE BMI AS A PREDICTOR OF PATIENT REPORTED OUTCOMES OF PRIMARY HIP REPLACEMENT SURGERY: A COMBINED ANALYSIS OF 4 PROSPECTIVE COHORT STUDIES R.N. Batra , A. Judge , M.K. Javaid , G.E. Thomas , D. Beard , D. Murray , P. Dieppe , K. Drienhoefer , K. Peter-Geunther , R. Field , C. Cooper , N.K. Arden . NIHR BioMed. Res. Unit, Univ. of Oxford, Oxford, United Kingdom; MRC Lifecourse Epidemiology Unit, Univ. of Southampton, Southampton, United Kingdom; 3 Peninsula Coll. of Med. and Dentistry, Plymouth, United Kingdom; Charite Univ.smedizin Berlin, Dept. of Orthop., Traumatology and Sports Med., Berlin, Germany; Univ. Hosp. Carl Gustav Carus, Technical Univ. of Dresden, Dresden, Germany; 6 Elective Orthop. Ctr., Epsom, United Kingdom Purpose: Total hip replacement (THR) is a successful surgical intervention, providing relief from pain, increasingmobility and improving quality of life for majority of patients. Within the literature some, but not all studies, have found that obesity is associated with worse patient reported outcomes (PROMs) of THR, and there is increasing concern that obesity may be used as a barrier to accessing surgery. Methods: We obtained information from 4 prospective cohort studies of patients receiving primary THR for osteoarthritis (OA): Exeter Primary Outcomes Study (EPOS) (n1⁄41589); EUROHIP (n1⁄4908); South West London Elective Orthopaedic Centre (SWLEOC) (n1⁄41523); and St. Helier (n1⁄4799). The primary outcome was the 12 month Oxford Hip Score (OHS) which is used to assess pain and function.For the EUROHIP study, we imputed the OHS from WOMAC scores using truncated regression. Confounding variables included: age, sex, SF-36 mental health, comorbidities, fixed flexion, analgesic use, college education, OA in other joints, expectation of less pain, radiographic KL only age and sex were available in all 4 cohorts. Linear regression (ANCOVA) is used to describe the association of BMI on the 12 month OHS, adjusting for the pre-operative OHS. Multiple imputation methods were used to handle missing data. In order to combine data across the 4 studies we used two methodological approaches: a) Meta-Analysis For each study, separate models are built to describe the association of BMI on outcome. Models are adjusted only for age and sex in order to construct related hypotheses in each study. Fixed effects metaanalysis is used to combine the results; b) Combining studies Data from all 4 studies are combined using multiple imputation methods to impute data on missing confounders, allowing the association of BMI on outcome to be adjusted for all potential confounders. Results: a) Meta-Analysis Adjusting for age and sex, for a 5 unit increase in BMI, the 12 month OHS decreases by 0.81 95%CI (0.55 1.08) units (Figure 1); Ă b) Combining Studies Adjusting for age and sex alone, for a 5 unit increase in BMI, the 12 month OHS decreases by 0.72 (0.46 0.99) units. Adjusting for all potential confounders, the effect is attenuated to 0.51 (0.09 0.92). Hence, for each 5 unit increase in BMI, the difference in post-op OHS becomes larger and more important. For example, compared to people with a normal BMI (20 25), those in the morbidly obese group (BMI 35 40) would have a post-op OHS that is 1.53 units lower. However, there is a substantial improvement in OHS after THR across all BMI groups, which greatly outweighs any difference in post-op score (Figure 2).