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Table 1 Risk of bias and confounding

From: Preoperative predictors for outcomes after total hip replacement in patients with osteoarthritis: a systematic review

First author, year Follow-up (years) Follow-up (% missing) Looking at independent effects
Bethge, 2010 [14] 1 28.9 Age, gender and self-efficacy expectations
Clement, 2011 [43] 1 ND Age
Clement, 2011 [47] 1 ND Age, SF-12 scores and length of stay
Cushnaghan, 2007 [34] Mean 8.8 48 cases Prediction model
53 controls
Davis, 2011 [35] 5 HHS: 28 Age, gender, operating consultant, and a diagnosis of cancer, atherosclerotic disease, cardiac disease, diabetes mellitus, osteoporosis and phlebitis
SF-36: 32
Duivenvoorden, 2013 [15] 1 31 Age, gender, time spent on waiting list and unbalanced characteristics between study population and patients lost to follow-up
Gandhi, 2010 [36] Mean 3.3 14 at 1 year follow-up Age, gender, BMI, SF-36 Mental Health (MH) scores, method of fixation (cemented vs uncemented), and comorbidity
Gordon, 2014 [37] 1 8 Age, gender, Charnley classification, previous contralateral THR, and preoperative pain VAS
Gordon, 2014 [38] 1 8 Gender, previous contralateral hip surgery, pain, and Charnley classification
Greene, 2014 [16] 1 66.7 Bayesian model averaging with age, gender, Charnley classification, presence of comorbidities, whether the included hip was the first or second in the time interval, marital status, and education level
Fortin, 2002 [39] 2 25.7a Age, gender, education, and comorbidity
Haverkamp, 2013 [28] Mean 2.3 18.6a No
Heiberg, 2013 [17] 1 27.3 Prediction model
Ieiri, 2013 [49] 1 and 3 ND Canonical correlation analysis
Johansson, 2010 [29] 2 ND No
Judge, 2014 [19] 1 30.8 Age, sex, SF-36 mental health, comorbidities, fixed flexion, analgesic use, college education, OA in other joints, expectation of less pain, radiological K&L grade, ASA grade, years of hip pain
Judge, 2013 [40] each year up to 5 20 at 1 year, 30 at 5 year Multivariable model
Judge, 2012 [48] Mean 8 61.3b Prediction model
Judge, 2011 [18] 1 31.6 Age, sex, school education, ASA grade, K&L grade, BMI, medication use
Katz, 2012 [27] 12 ND Patient age, sex, race, Medicaid eligibility, comorbidity and hospital and surgeon annual THA volume
Kennedy, 2011 [44] Up to 1.3 ND Age, gender, body mass index
Keurentjes, 2013 [20] 1.5–6 54.1a Age, sex, Charnley Comorbidity Classification and BMI
McHugh, 2013 [41] 1 11.7 Multivariable model
Meding, 2000 [22] Mean 2.7 11.4 at 1 year, 37.2 at 3 years, 64.8 at 5 years and 84.3 at 7 years Age and gender
Nikolajsen, 2006 [30] 1–1.5 6.4 No
Nilsdotter, 2003 [42] Mean 3.6 9.6 Multivariable model
Nilsdotter, 2002 [32] 1 16.2 No
Nilsdotter, 2001 [31] 1 11.9 No
Röder, 2007 [24] Mean 4.3 ND (registry study) Gender, age, and follow-up year
Rolfson, 2009 [23] 1 ND (registry study) Age, gender and comorbidity
Sadr Azodi, 2008 [25] 3 ND (registry study) Age at the time of surgery, calendar period, and fixation principle
Sarasqueta, 2012 [21] 1 29 Prediction model
Stickles, 2001 [26] 1 ND (registry study) No
Street, 2005 [33] 1 and 2 ND No
Tanaka, 2010 [45] 1 ND Age, sex, changes in the LLD, vertical ATD, femoral offset, and the horizontal and vertical position of the center of the femoral head, stage of hip OA (advanced or terminal); HHS, and the duration of OA
  1. SF-12 12-item Short Form Health Survey, HHS Harris Hip Score, SF-36 36-item Short Form Health Survey, BMI body mass index, MH mental health, THR total hip replacement, VAS visual analogue scale, OA osteoarthritis, K&L grade Kellgren-Lawrence, ASA American Society of Anesthesiologists, LLD leg length discrepancy, ATD articulotrochanteric distance
  2. ND not described or partly described
  3. aFor patients with THA and TKA, not separately described
  4. bAt 6 months