administrative qof data describing performance of family practices under the program were analyzed for the years 20042008 ( 3 ) .
data for each family practice included the number of registered diabetic subjects , the proportion of eligible subjects who achieved the targets , and the proportion of diabetic subjects excluded from evaluation of each target as  exceptions .
 exceptions arise because practices are permitted to identify some individuals as ineligible for evaluation if the target is regarded as clinically inappropriate ( 4 ) .
the targets included in this report were the percent of diabetic subjects with the last a1c 7.5% , with last blood pressure 145/85 mmhg , or with the last measured total cholesterol 5 mmol / l .
we estimated the total number of registered diabetic subjects , the total number excluded as ineligible , and the number ( and percent ) of subjects who achieved the target after allowing for exclusions .
the linear association between outcomes and year was estimated using robust standard errors to allow for repeated measures .
data were analyzed for family practices in england that remained independent and had more than 750 registered patients or more than 500 patients per doctor , in the study year .
data were analyzed for 8,423 practices in 20042005 , 8,264 in 20052006 , 8,192 in 20062007 , and 8,255 in 20072008 , representing 98% of all practices .
the median number of registered diabetic subjects per practice increased from 181 ( interquartile range [ iqr ] 107284 ) in 20042005 to 218 ( iqr 130342 ) in 20072008 ( table 1 ) .
the estimated resident population of england is 51 million ( 5 ) , giving an overall prevalence of 4% .
the median practice - specific proportion of diabetic subjects declared ineligible for the a1c target was 9.4% in 20042005 but declined to 8.7% in 20072008 ( p < 0.001 ) .
the median proportion excluded for the blood pressure target was 6.3% in 20042005 declining to 5.7% in 20072008 ( p < 0.001 ) and for cholesterol was 9.0% in 20042005 declining to 8.4% in 20072008 ( p < 0.001 ) .
the median practice - specific proportion achieving the a1c target of 7.5% increased from 59.1% in 20042005 to 66.7% in 20072008 ( table 1 ) .
the proportion achieving the blood pressure target of 145/85 mmhg increased from 70.9% in 20042005 to 80.2% in 20072008 .
the proportion achieving the cholesterol target of 5 mmol / l increased from 72.6% in 20042005 to 83.6% in 20072008 . the estimated annual increase in percent of diabetes subjects achieving targets was 3.03% ( 95% ci 2.953.10 ; p
< 0.001 ) for the a1c target , 3.26% ( 3.183.34 ; p < 0.001 ) for the blood pressure target , and 3.99% ( 3.924.07 ; p < 0.001 ) for the cholesterol target .
the total number of diabetic subjects in england achieving the a1c target , after allowing for exclusions from assessment , increased by 341,173 between 20042005 and 20072008 , representing 16% of diabetic subjects registered in 20072008 . over the same period ,
the number achieving the blood pressure target increased by 453,785 ( 22% of 20072008 registrations ) , and the number achieving the cholesterol target increased by 452,347 ( 22% of 20072008 registrations ) .
practices were classified as low performing if they achieved less than the 25th centile for the a1c target across all practices in 20062007 .
there were 57% of practices classified as low performing in 20042005 . among the 10 english regions , 69.9% of practices were low performing in london compared with
the overall proportion of low - performing practices declined to 47.4% in 20052006 , 25.0% in 20062007 , and 26.0% in 20072008 . in 20072008 , the proportion of low - performing practices ranged from 37.5% in london to 11.6% in the north east .
in the u.k . , the care of subjects with type 2 diabetes is increasingly undertaken outside of specialist clinics by family physicians and practice nurses in primary care . this has led to concerns that some patients may experience poor - quality care ( 6 ) . the new national contract for family practices introduced in 2004 appears to have achieved favorable results in its initial year ( 4,7 ) and may have contributed to reducing socioeconomic inequalities in care ( 8,9 ) .
lower - performing practices have shown the greatest improvements , and regional variations in care have reduced .
there has been a substantial increase in the proportion of all diabetic subjects achieving intermediate outcome targets . in our previous report ( 7 ) , we analyzed clinical data from individual patient records for 26 practices during the period of 20002003 that gave results consistent with administrative data from the qof .
two other reports , including data from the first or second years of qof , suggest that qof data are consistent with audits of individual patient records ( 10,11 ) . in a single group study , without any control practices ,
it is not possible to conclude that pay - for - performance incentives caused the observed changes .
there was already evidence of improving quality of care before the introduction of qof ( 7,12 ) .
the qof targets are designed for audit rather than best practice , and practitioners may be utilizing clinical practice guidelines that recommend more stringent targets .
recommendations for a widespread use of statins were introduced in many countries at the start of this period , leading to improvements even in the absence of pay - for - performance .
the greater improvement of low - performing practices may , in part , be accounted for by a ceiling effect , which restricted the potential improvement in high - performing practices .
we caution that it is not clear that proposed benefits from pay - for - performance would be observed if this model is adopted in systems with different organizational arrangements and models of practitioner remuneration .
 objective  to evaluate diabetes outcomes under a national  pay - for - performance  
 program.research design and methods  data were analyzed for 98% of all english family practices . 
 for each practice , the proportion of diabetic subjects with a1c 7.5% , blood pressure 145/85 mmhg , and cholesterol 5 mmol / l was determined . 
 practices achieving less than the 25th centile for the a1c target for 20062007 were classified as low performing.resultsthe proportion achieving the a1c target at the median practice increased from 59.1% ( interquartile range [ iqr ] 51.765.9 ) in 20042005 to 66.7% ( iqr 60.672.7 ) in 20072008 , blood pressure from 70.9% in 20042005 to 80.2% in 20072008 , and cholesterol from 72.6% in 20042005 to 83.6% in 20072008 . in 20042005 , 
 57% of practices were low performing ( range by region 42.469.9 ) . in 20072008 , 
 26% of practices were low performing ( range 11.637.5).conclusions  introduction of pay - for - performance may be one factor contributing to increasing achievement of targets and reducing problems of low performance . 