Table 1

Included study

StudyPopulationOutcomeResultsStudy designPotential modifiers or confoundersOther risk of bias
Wright et al2829 133 male residents of southwestern Finland, aged 50–69 years who smoked 5 or more yearsRelative risk of bladder cancerThe relative risk (RR) for bladder cancer was 1.15 (CI 0.86 to 1.55, p=0.38), suggesting that urine pH is not a major risk factor for bladder cancerProspective cohort studyEnergy intake, age, number of cigarettes smoked daily, number of years of smoking, α-tocopherol and β-carotene supplementation, BMI, total fluid intake, education level, place of residence, pack-years of smoking, smoking inhalation, smoking cessation, calcium, magnesium and/or potassium supplementsUsed renal NAE based on a validated formula based on nutrient intake and anthropometric information to estimate true urine pH
Effect modification by smoking duration, smoking dose, total fluid intake, BMI and intervention group was evaluated in stratified analysis
  • BMI, body mass index; NAE, net acid excretion; RR, relative risk.