Long-Term Effect of Population Screening for Diabetes on Cardiovascular Morbidity, Self-Rated Health, and Health Behavior

Justin B. Echouffo-Tcheugui; Rebecca K. Simmons; A. Toby Prevost; Kate M. Williams; Ann-Louise Kinmonth; Nicholas J. Wareham; Simon J. Griffin

doi:10.1370/afm.1737

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Figure 1
Practice and participant flow in the ADDITION-Cambridge diabetes screening trial.

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Table 1

Baseline Practice and Patient Characteristics in the ADDITION-Cambridge Screening Trial; Data are Median (Inter-quartile Range) Unless Otherwise Indicated

	Screening Group	No-Screening Control Group^a
Practices	n = 27	n = 5
Practice list size	6,610 (5,144–9,966)	8,827 (8,694–10,986)
Crude prevalence of diabetes, %	2.9 (2.5–3.5)	3.2 (3.0–3.4)
Physician full-time equivalents	3.5 (2.5–5.0)	4.5 (4.0–5.0)
Index of Multiple Deprivation score^b	11.7 (6.9–11.6)	15.7 (9.1–15.7)
Participants	n = 1,373	n = 572
Age, years	60 (54–65)	60 (54–65)
Men, n (%)	839 (61.1)	360 (62.9)
BMI, kg/m²	29.4 (27.7–32.3)	29.6 (27.8–32.2)
Cambridge diabetes risk score	0.36 (0.25–0.52)	0.38 (0.25–0.56)
Prescribed anti-hypertensive medication, n (%)	654 (47.6)	298 (52.1)
Prescribed steroids, n (%)	68 (5.0)	17 (3.0)

BMI = body mass index.
↵a There were no statistically significant differences between groups.
↵b The Index of Multiple Deprivation combines a number of indicators, chosen to cover a range of economic, social and housing issues, into a single deprivation score for each small area in England. This allows each area to be ranked relative to one another according to their level of deprivation. A high Index of Multiple Deprivation score indicates a high level of deprivation.

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Table 2

Impact of Screening on Cardiovascular Morbidity and the Prescription of Cardioprotective Drugs in the ADDITION-Cambridge Trial at 7-year Follow-up

	Screening Group	No-screening Control Group	Odds Ratio (95%CI)^a
Cardiovascular morbidity, n (%)
Self-reported cardiovascular events^b	142 (12.4)	67 (13.5)	0.90 (0.71–1.15)
Self-reported hypertension	809 (60.9)	352 (63.4)	0.90 (0.75–1.08)
Self-reported dyslipidemia	502 (41.2)	254 (48.3)	0.75 (0.64–0.88)
Prescribed medication, n (%)
Antihypertensive drugs	853 (72.5)	369 (74.7)	0.89 (0.73–1.10)
ACE inhibitors	546 (46.4)	244 (49.4)	0.89 (0.75–1.06)
Lipid lowering drugs	507 (43.1)	244 (49.4)	0.78 (0.63–0.95)
Antiplatelet drugs	335 (28.5)	185 (37.5)	0.67 (0.53–0.83)
Glucose lowering drugs	97 (8.3)	48 (9.7)	0.84 (0.57–1.21)

ACE = angiotensin-converting enzyme.
↵a Accounting for clustering by general practice.
↵b A cardiovascular event was defined as myocardial infarction or stroke.

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Table 3

Impact of Screening on Self-rated Health Status and Self-reported Health Behaviors in the ADDITION-Cambridge Trial at 7-year Follow-up

	Screening Group	No-screening Control Group	Intervention Effect (95%CI)^a
Self-rated health status
Mean SF-8 physical health summary score (scale 0 to 100), score (SD)	47.4 (9.8)	47.8 (10.3)	−0.33 (−1.80 to 1.14)
Mean SF-8 mental health summary score (scale 0 to 100), score (SD)	51.8 (8.6)	52.2 (8.1)	−0.38 (−1.33 to 0.57)
Mean EQ-5D score (scale −0.3 to 1.0), score (SD)	0.87 (0.16)	0.87 (0.15)	0.002 (−0.02 to 0.02)
Mean EuroQol visual acuity score (scale 0 to 100), score (SD)	74.5 (16.5)	73.7 (17.2)	0.80 (−1.28 to 2.87)
Self-reported health behavior
Current smoker, n (%)	143 (10.5)	61 (10.7)	0.97 (0.72–1.32)
Alcohol consumption (units per week), mean (SD)	8.2 (11.9)	8.1 (11.1)	0.14 (−1.07 to 1.35)
1 or more portions fresh fruit per day, n (%)	627 (46.4)	249 (43.8)	1.11 (0.93–1.33)
1 or more portions green leafy vegetables per day, n (%)	339 (25.2)	117 (20.7)	1.28 (0.99–1.66)
1 or more portions other vegetables per day, n (%)	382 (28.5)	142 (25.1)	1.19 (0.99–1.43)
5 or more portions oily fish per week, n (%)	27 (2.1)	10 (1.8)	1.14 (0.61–2.11)
5 or more portions meat products per week, n (%)	104 (7.8)	51 (9.1)	0.84 (0.64–1.11)
1 or more portions whole meal (brown) bread per day, n (%)	414 (30.8)	167 (29.9)	1.04 (0.89–1.22)
Total physical activity (MET-hours per week), mean (SD)	45.1 (51.3)	44.6 (51.9)	0.50 (−4.08 to 5.07)
Vigorous activity (MET-hours per week), mean (SD)	16.2 (31.7)	15.3 (32.5)	0.89 (−2.09 to 3.86)
Walking activity (MET-hours per week), mean (SD)	22.6 (21.1)	21.2 (21.0)	1.35 (−1.17 to 3.86)
Sedentary time (hours per day), mean (SD)	5.3 (2.7)	5.4 (2.8)	−0.11 (−0.32 to 0.09)
Number of hospital admissions in past 3 months, mean (SD)	0.11 (0.37)	0.13 (0.44)	0.85 (0.58–1.25)^b
Number of family physician consultations in past 3 months, mean (SD)	1.1 (1.3)	1.2 (1.5)	0.93 (0.78–1.12)^b
Number of nurse consultations in past 3 months, mean (SD)	0.8 (1.7)	0.8 (1.7)	1.04 (0.79–1.36)^b

SF-8 = 8-item short form health survey; EQ-5D = EuroQual measure of health outcome; MET = Metabolic equivalents of physical activity.
↵a Beta coefficients (95% CI) for continuous outcomes (representing the mean difference between groups) and odds ratios (95% CI) for categorical outcomes, accounting for clustering by general practice.
↵b Negative binomial regression (appropriate for over-dispersed count data) was used to compare the number of hospital admissions, family physician consultations, and nurse consultations. The effect sizes can be interpreted as ratios of incidences.

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The Article in Brief

Long-Term Effect of Population Screening for Diabetes on Cardiovascular Morbidity, Self-Rated Health, and Health Behavior

Simon J. Griffin , and colleagues

Background Many organizations recommend population screening for diabetes. This study assesses the long-term effects of such screening.

What This Study Found At the population level, screening high risk individuals for diabetes appears to have limited impact on cardiovascular disease, self-rated health status and health behavior. In a study of 18,875 individuals aged 40 to 69 years at high risk of diabetes, 2.9 percent of those eligible for screening were diagnosed with diabetes. After seven years, there were no significant differences between the screening and control groups in terms of reported heart attack or stroke, self-rated health status, physical activity, smoking status or alcohol consumption. Diabetes screening did not have a negative effect on self-rated functional status or health utility and did not lead to unhealthy behaviors due to false reassurance or to an increase in health service use.

Implications

The authors see no long-term beneficial effect of screening for type 2 diabetes at the population level. They conclude that a single round of screening may be associated with benefits among the minority whose previously undiagnosed diabetes is detected, but it appears unlikely to affect the health of the population as a whole.