GENERAL COMMENTS

The authors might be missing the effects of different cultural mix within London. According to the Census for 2011, 63% Londoners were born in the UK compared to 90% for the rest of the population in England. Within England, the North West also has the largest proportion of population born in the UK (95%) and Appendix Table 3 shows that the region consistently shows the largest differences in comparison with London. Apart from possible language problems and difficulties in communication, it might be that, in London, a large proportion of patients have different cultural expectations or that a significant number of staff communicate with patients in different ways.

The authors run 64 comparisons using a 5% significance level. For this number, an adjustment for multiple comparisons should be made. Further, given the power of the study (69,086 questionnaires) it is rather too easy to reach this level of significance for even minor differences between groups. I think it would be more appropriate to set up a threshold for the odds ratios and report on how many questions reach this.