1-time Screening Research Articles

Cumulative evaluation of a quantitative immunochemical fecal occult blood test to determine its optimal clinical use

Quantified, human hemoglobin (Hb)-specific, immunochemical fecal occult blood test (IFOBT) measurements are now used for colorectal cancer (CRC) screening. The objective was to evaluate sensitivity and specificity for CRC and advanced adenomatous polyps (APs) by the fecal Hb threshold used to determine a positive test and the number of IFOBTs prepared per test, so as to determine the least number of colonoscopies required to detect a neoplasm. Cumulative data were analyzed from a prospective cross-sectional double-blind study of 1682 consecutive, ambulatory, nonbleeding colonoscopy patients who volunteered for IFOBTs, most of above average risk, from 3 ambulatory-endoscopy centers. Fecal Hb was measured in 3 samples and analyzed by an automated instrument, and the highest result >or=50 ng Hb/mL of buffer was related to findings. Colonoscopy identified CRC in 20 patients and advanced APs in 129. Sensitivity for either was best when any of 3 tests had >or=50 ng Hb/mL of buffer; sensitivity was 61.1% (95% confidence interval [CI], 53.2-68.9), and specificity was 87.8% (95% CI, 86.2-89.4). Positive tests identified 100% of CRCs and 55% of advanced APs every 3.1 colonoscopies. Sensitivity of a single test at the commonly used 100-ng Hb/mL threshold was lower at 31.5% (95% CI, 24.1-39.0) (P<.001), but specificity was higher at 96.4% (95% CI, 95.5-97.3) (P<.001). Positive tests identified 65% of CRCs and 26.4% of advanced APs every 2.2 colonoscopies. The fecal Hb cutoff chosen by the screener and the number of samples collected per patient determine sensitivity and specificity for CRC/advanced AP; these factors determine the number of colonoscopies needed for positive tests and neoplasia yield. This information provides guidelines for IFOBT screening. Limitations are 1-time screening and most examinees not being at average risk for CRC.

A Model of the Economic Impact of a Bipolar Disorder Screening Program in Primary Care

Unrecognized bipolar disorder in patients presenting with a major depressive episode may lead to delayed diagnosis, inappropriate treatment, and excessive costs. This study models the cost effectiveness of screening for bipolar disorder among adults presenting for the first time with symptoms of major depressive disorder. A decision-analysis model was used to evaluate the outcomes and cost over 5 years of screening versus not screening for bipolar disorder. Screening was defined as a 1-time administration of the Mood Disorder Questionnaire at the initial visit followed by referral to a psychiatrist for patients screening positive for bipolar disorder. Health states included correctly diagnosed bipolar disorder, unrecognized bipolar disorder, and correctly diagnosed major depressive episodes. Model outcomes included rates of correct diagnosis of bipolar disorder and discounted costs (2006 US dollars) of screening and treating major depressive episodes. Literature was the primary source of data and was collected from September 2007 through March 2009. According to the model, 1,000 adults in a health plan with 1 million adult members annually present with symptoms of major depressive disorder. An additional 38 patients were correctly diagnosed with depression (unipolar or a major depressive episode) or bipolar disorder (440 with screening vs 402 without screening) through a 1-time screening for bipolar disorder. Estimated 5-year discounted costs per patient were $36,044 without screening and $34,107 with screening (savings of $1,937). Accordingly, total 5-year budgetary savings were estimated at $1.94 million. Results were most sensitive to difference in treatment costs for patients with recognized versus unrecognized bipolar disorder. A 1-time screening program for bipolar disorder, when patients first present with a major depressive episode, can reduce health care costs to managed-care plans.

15-Year Followup of a Population Based Prostate Cancer Screening Study

We evaluated long-term survival in attendees and nonattendees of a 1-time screening for prostate cancer. A total of 2,400 men 55 to 70 years old in 1988 were randomly selected and invited to a screening for prostate cancer. Of the invited men 1,782 (74%) attended. Screening attendees were examined with digital rectal examination, transrectal ultrasound and prostate specific antigen analysis. When cancer was suspected, prostate biopsies were taken. A total of 65 men with prostate cancer were detected by this procedure. The entire source population comprising 27,204 men, including 618 nonattendees (26%), was followed for prostate cancer diagnosis and survival for 15 years. Incidence rate ratios were calculated using Poisson regression models. We found no effect of this screening procedure on the risk of death from prostate cancer and other causes of death (incidence rate ratio 1.10, 95% CI 0.83-1.46 and 0.98, 95% CI 0.92-1.05, respectively) when comparing all invited men with the source population. However, attending the screening program was associated with a significantly decreased risk of death from causes other than prostate cancer (vs source population incidence rate ratio 0.82, 95% CI 0.76-0.90). In contrast, the corresponding incidence rate ratio in nonattendees was 1.53 (95% CI 1.37-1.71). We found no evidence of a beneficial effect of this specific screening procedure but strong evidence of a difference in overall survival in screening attendees and nonattendees. These findings should be considered when interpreting previous and upcoming studies of the effect of screening programs.

Abdominal Aortic Aneurysms, Increasing Infrarenal Aortic Diameter, and Risk of Total Mortality and Incident Cardiovascular Disease Events

Long-term data describing small abdominal aortic aneurysms (AAAs) and increasing infrarenal aortic diameters and their relationship to future surgical repair, total mortality, and incident cardiovascular disease (CVD) events, particularly among women, are sparse. In 1992 to 1993, 4734 Cardiovascular Health Study participants > or = 65 years old had an abdominal aortic ultrasound evaluation. Of those screened, 416 had an AAA (infrarenal aortic diameter > or = 3.0 cm or an infrarenal/suprarenal ratio > or = 1.2). By 2002, there were 56 surgical AAA repairs and 10 AAA-related deaths. A single ultrasound screening demonstrated that aneurysm dilation > or = 3 cm identified 68% of all AAA repairs over the next 10 years and 6 of the 10 AAA-related deaths in 4% of the total population and that a > or = 2.5-cm dilation identified 91% of all AAA repairs and 9 of the 10 deaths in 10% of the total population. With adjusted Cox proportional hazard models, AAAs were associated with a higher risk of total mortality (hazard ratio 1.44, 95% confidence interval 1.25 to 1.66) and incident CVD events (hazard ratio 1.52, 95% confidence interval 1.25 to 1.85). Compared with diameters < 2.0 cm, infrarenal aortic diameters 2.0 to < 3.0 cm were associated with increased risk of incident CVD events in women and total mortality in men. This study suggests that a 1-time screening of the abdominal aorta can acceptably identify individuals with a clinically significant AAA. Infrarenal aortic diameters > 2.0 cm are associated with a significantly increased risk of future CVD events and total mortality.

Preventing Stroke Among Children With Sickle Cell Anemia: An Analysis of Strategies That Involve Transcranial Doppler Testing and Chronic Transfusion

Transcranial Doppler ultrasonography can identify children with sickle cell anemia who are at elevated risk of stroke and may benefit from chronic transfusions. Uncertainty about the risk/benefit trade-offs of chronic transfusion has led some clinicians to decide not to offer transcranial Doppler ultrasonography screening. Our goals were to (1) compare the projected benefits and risks of 6 primary stroke-prevention strategies, (2) estimate the optimal frequency of screening, and (3) identify key assumptions that influence the risk/benefit relationship. We designed a decision model to compare 6 primary stroke-prevention strategies: (1) annual transcranial Doppler ultrasonography screening until age 16 with children at high risk of stroke receiving monthly transfusion for life; (2) annual transcranial Doppler ultrasonography until age 16 with transfusions until age 18; (3) biannual transcranial Doppler ultrasonography until age 16 with transfusions until age 18; (4) annual transcranial Doppler ultrasonography until age 10 with transfusion until age 18; (5) 1-time screening at age 2 with transfusion until age 18; and (6) no intervention. Assumptions were derived from the published literature. For a hypothetical cohort of 2-year-old children, the optimal strategy was transcranial Doppler ultrasonography screening annually until age 10 with children at high risk receiving monthly transfusions until age 18. The optimal strategy would prevent 32% of strokes predicted to occur without intervention. The optimal strategy led to benefits similar to more intensive screening and transfusion strategies but resulted in fewer adverse events. All the intervention strategies resulted in net losses in life expectancy, because the projected mortality averted by stroke prevention was outweighed by the projected increase in mortality from transfusion. Results were sensitive to adherence rates to iron-chelation therapy. The optimal stroke-prevention strategy was projected to be annual transcranial Doppler ultrasonography screening until age 10 with transfusion for children at high risk until age 18. Better adherence to chelation therapy would improve life expectancy in all intervention strategies.