In a study of people at high risk of diabetes, screening for the disease led to no reduction in mortality over 10 years, according to results published online Oct. 4 in Lancet.
"This study increases the doubt about the value of wide-scale screening for undiagnosed diabetes alone," accompanying editorialist Michael M. Engelgau, MD, of the National Center for Chronic Disease Control and Prevention at the Centers for Disease Control and Prevention in Atlanta, wrote in an email to Cardiovascular Business. "[The authors] deserve credit for tackling the screening quandary head-on like no other study has done."
In this study, Rebecca K. Simmons, PhD, of Addenbrooke’s Hospital in Cambridge, England, and colleagues used data from the ADDITION-Cambridge trial, a clinic-level cluster randomized study, to assess mortality among patients of primary care practices in eastern England. The researchers included 32 primary care practices, which were divided into screening or no screening (control group, which comprised five practices). The screening practices offered diabetes screening to patients aged 40-69 years considered at high risk for diabetes.
Patients whose screenings resulted in a diabetes diagnosis were offered intensive treatment at one group of clinics (14 practices) and standard treatment at the other group (13 practices). Patients were followed for 10 years; all-cause mortality was the primary endpoint, death from cardiovascular disease, cancer, other causes and diabetes-related death were secondary endpoints.
Screening was conducted between January 2002 and March 2006; deaths were recorded through Nov. 28, 2011. There were 16,047 eligible people in the screening group, of which 73 percent attended the first-stage screening, and 466 were diagnosed with diabetes. The mean duration of follow-up was 9.6 years.
There were 1,532 deaths in the screening group and 377 deaths in the control group. The leading cause of death was cancer, and the authors reported no significant differences between the screening and control groups for all-cause mortality, cardiovascular mortality, cancer mortality, other causes of death and diabetes-related mortality.
The authors noted that computer modeling had predicted that screening would have a significant impact on mortality, and postulated that their findings might be a result of :
- Dilution of the effect of screening because of widespread opportunistic screening in the U.K.;
- Improvement in the detection and management of cardiovascular disease risk factors, including diabetes in primary care practices in the U.K.; and
- Possible overestimation of the prevalence of undiagnosed diabetes.
They noted also that the study population was taken from a relatively affluent area in England, and that this factor may have had an impact on their findings.
Based on their results, the authors wrote, "If population-based screening for diabetes is to be implemented, it should be undertaken alongside assessment and management of risk factors for diabetes and cardiovascular disease and population level preventive strategies targeting underlying determinants of these diseases."
In an accompanying comment, Engelgau and Edward W. Gregg, PhD, of the National Center for Chronic Disease Control and Prevention at the Centers for Disease Control and Prevention in Atlanta, pointed out that screening has associated costs, harms and no clear benefit to long-term outcomes.
However, Engelgau and Gregg cautioned that the results may not be readily or appropriately transferrable to other populations. "The study populations' prevalence of newly diagnosed diabetics was low (three percent) and countries with a higher prevalence of undiagnosed diabetes and low care quality could conceivably see a wider range and magnitude of benefits, assuming adequate resources are available to care for the added burden of newly detected cases," they wrote.
In addition, Engelgau and Gregg noted that the study monitored mortality only and did not assess potential benefits of screening such as chronic disease risk factor improvement, morbidity, quality of life and costs of care. "Ultimately, the judgment on screening will depend on more than just mortality as an outcome," they wrote.
Engelgau added in his email, "Future diabetes screening policy will likely be linked with diabetes prevention efforts where studies suggest that screening for diabetes and high-risk states in combination is more effective than screening for diabetes