This is the first study to undertake a comparison of quality of care between the four countries of the UK using QOF data. The key findings are that the quality of care measured by the QOF is generally highest in Northern Ireland and lowest in Wales, and that the financial incentive for quality is proportionately lower in Wales and Scotland. The strength of the study is that it uses clinical quality data for important diseases collected to a common definition for 96% of UK general practices. Although QOF is not a fully comprehensive quality dataset, it exceeds all previous cross-jurisdictional comparisons in terms of the scope and coverage of primary care clinical activity. However, the analysis is limited by the nature of the data, which reflects its origin in a payment, rather than a quality monitoring, system. In particular, the data are at practice level, which makes patient-level case-mix adjustment impossible. Although exception reporting of patients who are unsuitable for or who decline care should function as a crude form of patient level case-mix adjustment, exception reporting is under practice control, potentially serves practices' financial self-interests, and could systematically vary by country. However, the overall conclusions are unchanged whether examining quality measures that allow exception reporting or not. Finally, although QOF data are consistent, other practice level variables are not (for example, data on practice employed staff) which limits exploration of potential resource or organisational explanations for the differences that are observed.
Cross-jurisdictional comparisons using routine data are helpful in identifying broad trends and areas of concern. QOF adds to existing comparisons because of its focus on clinical quality, and its near comprehensive coverage. However, the lack of comparable data on practice resources and organisation means that it is difficult to account for the differences seen beyond generating hypotheses for more detailed examination.
The most notable finding is that quality of CHD, stroke and diabetes care in Wales on these measures is significantly lower than elsewhere in the UK for complex care processes, intermediate outcomes, and treatments. Although varying prevalence between countries means that practices in Wales are, on average, less financially incentivised for quality under QOF, this seems unlikely to have directly influenced motivation to deliver high quality in the first year because the detailed link between performance and reward in the payment system is opaque.  However, in the longer term, lower payment rates per patient for the same level of quality might be expected to affect quality. Notably, the measures for which Wales consistently performs poorly are those for which practices are more likely to require collaboration with larger NHS organisations (organisation of diabetes care, effective management of intermediate outcomes, influenza vaccination), rather than simple processes directly under practice control. The evidence from this study is therefore consistent with previously identified waiting time problems being symptomatic of a wider quality problem within NHS Wales, and requires closer examination.
NHS Scotland has generally higher quality than NHS England, particularly on the complex process measures for diabetes. The largest difference is for diabetic foot examination. In theory, Scottish policy on the co-ordination of care for whole populations by managed clinical networks might be expected to have a beneficial impact on such indicators. This finding is also consistent with other evidence of higher quality in Scotland for services requiring area-based co-ordination like immunisation and breast screening.  On average, Scotland has substantially more whole time equivalent GPs per 1000 registered patients than England which might also be expected to lead to higher QOF performance (although the higher prevalence of cardiovascular disease implies more work per GP than registered list differences alone imply).
The generally small differences that we have observed may be reassuring for NHS England, where the focus of targets and market reform on acute services and elective surgery does not appear to have seriously affected quality of chronic disease care, at least for these incentivised measures. However, the true test of the success of a policy of increasing market reform and the setting of targets in primary care will require additional research on how the introduction of the QOF has impacted on those areas not covered by the GMS contract.
Finally, it is striking that clinical quality in Northern Ireland is higher than in the rest of the UK. This may reflect greater population or health service stability, for example because Northern Ireland has experienced less diversion of management and clinical attention due to repeated re-organisation. It may also in part be a consequence of Northern Ireland having a younger population compared to the UK as a whole with evidence from England suggesting that practices with a higher proportion of over 65 year-olds have lower achievement.