Table 1.

Included study

Study	Population	Outcome	Results	Study design	Potential modifiers or confounders	Other risk of bias
Wright et al28	29 133 male residents of southwestern Finland, aged 50–69 years who smoked 5 or more years	Relative risk of bladder cancer	The 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 cancer	Prospective cohort study	Energy 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 supplements	Used 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.