Late last year, The NHS Atlas of Variation in Healthcare was published by the Department of Health,1 inspired by the American Dartmouth Atlas of Health Care.2 In the linked Analysis article (doi:10.1136/bmj.d1513), John Wennberg, the “father” of the Dartmouth atlas, writes approvingly of the NHS atlas.3

For a wide range of selected specialties identified by Department of Health national clinical directors, it documents variations by primary care trust in treatment and investigation rates, care processes, resource use, expenditure, and outcomes. The idea behind the atlas is that publicising these variations and giving commissioners and providers tools to analyse and investigate them will help reduce avoidable differences between areas, thereby improving the effectiveness and efficiency of the English NHS.

Like the Dartmouth atlas, the NHS atlas shows large (typically twofold to fivefold, and often much higher) unexplained variations on many indicators, although the differences between the top and the bottom are …