Table 6 KneeOA and climbing stairs: details of the studies
ReferenceStudy populationAge (years)Participation rate (%)Exposure measured byDiagnostic criteriaAdjusted for/ Matched byComparisonsResults (OR, 95% CI)DesignQuality of the study (+, ++, +++)/Strength/Weakness
Cooper et al, 199420Grade 3–4 OA cases: 30 men and 79 womenControls: 218 age- and sex-matched (without knee pain) from a large general practice55–90Mean 73?QuestionnaireOccupational historySymptomatic kneeOA Kellgren and Lawrence grade 3–4TFJ±PFJWeight-bearing APBMI, Heberden’s nodesClimbing stairs >30 flights of stairs per day vs no stair-climbing2.7, 1.2 to 6.1Case–control++Strength: Weight-bearing radiographs, inclusion of PFJ OASubjects with moderate and severe symptomatic OAWeakness: Retrospectively exposure measurement (risk of recall bias) Small number of male participants among cases, small number of cases and controls which have been employed in occupations with climbing stairs
Sandmark et al, 200027Cases: 325 men, 300 women with TKRControls: 264 men, 284 womenFrom 14 counties in Sweden55–7080Interviews, questionnaireOccupational history(Lifts at work (kg))TKR between 1991–1993BMI, smoking, sports activity, Age-matchedClimbing stairsMediumMenWomenHighMenWomen1.2, 0.8 to 1.91.7, 1.1 to 2.51.2, 0.7 to 2.11.4, 0.8 to 2.3Case–control+++Strength: High participation rate, good description of material and methods. Adjustment for relevant confoundersWeakness: Case definition: TKR (risk of selection bias) Exposure assessment retrospective (risk of recall bias). Use of job titles (risk of misclassification)
Coggon et al, 200025Cases: 518 (205 men 313 women) waiting for TKRControls: 518 (205 men 313 women) from the same communityFrom three English districts in a 2-year period47–93Mean: 7355%InterviewOccupation held for >1 year from school ageWaiting for surgeryBMIHeberden’s nodesPrevious knee injuriesMatched by sex and ageClimbing a ladder or flight of stairs >30 times per day vs no climbingMenWomen2.3, 1.3 to 4.00.7, 0.3 to 1.6Case–control+++Strength: High number of participants, interviews with specification of different physical activitiesWeakness: Exposure data collected retrospectively (risk of recall bias). Low participation rate especially among controls. Case definition: placed on a waiting list for TKR (risk of selection bias)
Lau et al, 200026Cases: 166 men, 492 women hospitalised in Hong Kong with kneeOAControls: 166 age- and sex-matched from general practice in the same regionInterviewJob in which they had worked for the longest period before symptoms28% had TKR, 15% waiting for TKR, the restGrade 3–4 OAMatched by sex and ageClimbing stairs >15 flights per dayMenWomen4.1, 2.1 to 8.26.1, 3.5 to 10.8Case–control+++Strength: Design and materials described. Controls without radiological kneeOA and subjects with meniscal lesions excludedWeakness: Case definition: OA grade 1–4. 66% of cases had grade 1 OA, only 10% grade 3–4 OA (risk of misclassification) Retrospective exposure assessment (risk of recall bias)
Manninen et al, 200230Cases: 55 men, 226 womenControls: 524 age- and sex-matched from same population55–75Cases: 78.5%Control: 65.6%Telephone interviewPhysical demands before the age of 49 yearsFirst surgery for kneeOABMIKnee injuryClimbing vs low exposureMedium levelMenWomenHigh level MenWomen3.06, 1.25 to 7.51.08, 0.71 to 1.632.79, 0.96 to 8.21.5, 0.81 to 2.77Case–control+++Strength: High number of female participants, interviews with specification of different physical activities. Weakness: Exposure assessment: retrospective (risk of recall bias) Few men (n = 55) Cases defined as TKR (risk of selection bias)
  • PFJ, patello-femoral joint; TFJ, tibio-femoral joint.

  • +, Poor quality score 1–5; ++, medium quality score 6–10; +++, high quality score >10.