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.
Simmons
R K
RK
MRC Epidemiology Unit, Institute of Metabolic Science, Box 285, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK.
Rahman
M
M
Jakes
R W
RW
Yuyun
M F
MF
Niggebrugge
A R
AR
Hennings
S H
SH
Williams
D R R
DR
Wareham
N J
NJ
Griffin
S J
SJ
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