Effect of population screening for type 2 diabetes on mortality: long-term follow-up of the Ely cohort.
OBJECTIVE
The aim of this study was to assess the impact of invitation to screening for type 2 diabetes and related cardiovascular risk factors on population mortality.


METHODS
This was a parallel-group population-based cohort study including all men and women aged 40-65 years, free of known diabetes, registered with a single practice in Ely, UK (n = 4,936). In 1990-1992, approximately one-third (n = 1,705) were randomly selected to receive an invitation to screening for diabetes (with an OGTT) and related cardiovascular risk factors. In the remaining two-thirds of the population, 1,705 individuals were randomly selected for invitation to screening in 2000-2003 and 1,526 were not invited at any point during the follow-up period. All individuals were flagged for mortality until January 2008.


RESULTS
There were 345 deaths between 1990 and 1999 (median 10 years follow-up). Compared with those not invited, individuals who were invited to the 1990-1992 screening round had a non-significant 21% lower all-cause mortality (HR 0.79 [95% CI 0.63-1.00], p = 0.05) after adjustment for age, sex and deprivation. There were 291 deaths between 2000 and 2008 (median 8 years follow-up), with no significant difference in mortality between invited and non-invited participants in 2000-2003. Compared with the non-invited group, participants who attended for screening at any time point had a significantly lower mortality and those who did not attend had a significantly higher mortality.


CONCLUSIONS
Invitation to screening was associated with a non-significant reduction in mortality in the Ely cohort between 1990 and 1999, but this was not replicated in the period 2000-2008. This study contributes to the evidence concerning the potential benefits of population screening for diabetes and related cardiovascular risk factors.
MRC Epidemiology Unit, Institute of Metabolic Science, Box 285, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK.
R K
RK
Simmons
M
M
Rahman
R W
RW
Jakes
M F
MF
Yuyun
A R
AR
Niggebrugge
S H
SH
Hennings
D R R
DR
Williams
N J
NJ
Wareham
S J
SJ
Griffin
D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000503:physiopathology; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000175:diagnosis* / Q000401:mortality*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models