Field validity and spatial accuracy of Food Standards Agency Food Hygiene Rating scheme data for England

Background The study aimed to evaluate the validity and spatial accuracy of the Food Standards Agency Food Hygiene Rating online data through a field audit. Methods A field audit was conducted in five Lower Layer Super Output Areas (LSOAs) in the North East of England. LSOAs were purposively selected from the top and bottom quintiles of the Index of Multiple Deprivation and from urban and rural areas. The FHRS data validity against the field data was measured as Positive Predictive Values (PPV) and sensitivity. Spatial accuracy was evaluated via mean difference in straight line distances between the FHRS coordinates and the field coordinates. Results In all, 182 premises were present in the field, of which 162 were in the FHRS data giving a sensitivity of 89%. Eight outlets recorded in the FHRS data were absent in the field, giving a PPV of 95%.The mean difference in the geographical coordinates of the field audit compared to the FHRS was 110 m, and <100 m for 77% of outlets. Conclusions After an evaluation of the validity and spatial accuracy of the FHRS data, the results suggest that it is a useful dataset for surveillance of the food environment and for intervention evaluation.