TableĀ 1

Quality assessment of studies n (%)

Did the study address a clearly focused question?108 (100%)00
Was the study population recruited in an acceptable way?105 (97.2%)03 (2.8%)
Did it include all the population or describe the population not included?97 (89.8%)7 (6.5%)4 (3.7%)
Was the method used to calculate the distance/travel time reported accurately?85 (81.5%)23 (18.5%)0
Was the health outcome accurately measured to minimise bias?108 (100%)00
Have important confounding factors been taken account of in the design or analysis?90 (83.3%)17 (15.7%)1 (1%)
Is the funding source external to the organisation?68 (63.0%)16 (14.8%)24 (22.2%)
Was the research peer reviewed?101 (93.5%)07 (6.5%)