Monitoring initial response to Angiotensin-converting enzyme inhibitor-based regimens: an individual patient data meta-analysis from randomized, placebo-controlled trials

Most clinicians monitor blood pressure to estimate a patient's response to blood pressure-lowering therapy. However, the apparent change may not actually reflect the effect of the treatment, because a person's blood pressure varies considerably even without the administration of drug therapy. We estimated random background within-person variation, apparent between-person variation, and true between-person variation in blood pressure response to angiotensin-converting enzyme inhibitors after 3 months. We used meta-analytic mixed models to analyze individual patient data from 28 281 participants in 7 randomized, controlled trials from the Blood Pressure Lowering Trialists Collaboration. The apparent between-person variation in response was large, with SDs for change in systolic blood pressure/diastolic blood pressure of 15.2/8.5 mm Hg. Within-person variation was also large, with SDs for change in systolic blood pressure/diastolic blood pressure of 14.9/8.45 mm Hg. The true between-person variation in response was small, with SDs for change in systolic blood pressure/diastolic blood pressure of 2.6/1.0 mm Hg. The proportion of the apparent between-person variation in response that was attributed to true between-person variation was only 3% for systolic blood pressure and 1% for diastolic blood pressure. In conclusion, most of the apparent variation in response is not because of true variation but is a consequence of background within-person fluctuation in day-to-day blood pressure levels. Instead of monitoring an individual's blood pressure response, a better approach may be to simply assume the mean treatment effect.

Who needs colonoscopy to identify colorectal cancer? Bowel symptoms do not add substantially to age and other medical history

BACKGROUND

Many bodies advise that people with bowel symptoms undergo colonoscopy to detect colorectal cancer.

AIM

To determine which bowel symptoms predict cancer on colonoscopy.

METHODS

Information was collected on symptoms, demographics and medical history from patients subsequently undergoing colonoscopy. Multiple logistic regression modelling was used to identify predictors of colorectal cancer. An ROC curve was estimated for each model, and the area under the curve (AUC) was computed.

RESULTS

Cancer was found in 159 patients and no cancer or adenoma in 7577 patients. Bowel symptoms that predicted cancer were rectal bleeding, change in bowel habit and rectal mucus. Prediction was the strongest in patients who had symptoms at least weekly and commencing within the previous 12 months; abdominal pain was predictive only in such patients. The odds ratios never exceeded 4.27. A model based on age, gender, and medical history was highly predictive (AUC = 0.79). Adding symptoms to this model increased the AUC to 0.85.

CONCLUSIONS

This model predicts patients in whom colonoscopy will have the highest yield. Conversely, colonoscopy can be avoided in people at low risk: in our study, 95% of cancers could have been detected by doing only 60% of the colonoscopies.

The accuracy of clinical symptoms and signs for the diagnosis of serious bacterial infection in young febrile children: prospective cohort study of 15 781 febrile illnesses

OBJECTIVES

To evaluate current processes by which young children presenting with a febrile illness but suspected of having serious bacterial infection are diagnosed and treated, and to develop and test a multivariable model to distinguish serious bacterial infections from self limiting non-bacterial illnesses. Design Two year prospective cohort study. Setting The emergency department of The Children's Hospital at Westmead, Westmead, Australia.

PARTICIPANTS

Children aged less than 5 years presenting with a febrile illness between 1 July 2004 and 30 June 2006.

INTERVENTION

A standardised clinical evaluation that included mandatory entry of 40 clinical features into the hospital's electronic record keeping system was performed by physicians. Serious bacterial infections were confirmed or excluded using standard radiological and microbiological tests and follow-up. Main outcome measures Diagnosis of one of three key types of serious bacterial infection (urinary tract infection, pneumonia, and bacteraemia), and the accuracy of both our clinical decision making model and clinician judgment in making these diagnoses.

RESULTS

We had follow-up data for 93% of the 15 781 instances of febrile illnesses recorded during the study period. The combined prevalence of any of the three infections of interest (urinary tract infection, pneumonia, or bacteraemia) was 7.2% (1120/15 781, 95% confidence interval (CI) 6.7% to 7.5%), with urinary tract infection the diagnosis in 543 (3.4%) cases of febrile illness (95% CI 3.2% to 3.7%), pneumonia in 533 (3.4%) cases (95% CI 3.1% to 3.7%), and bacteraemia in 64 (0.4%) cases (95% CI 0.3% to 0.5%). Almost all (>94%) of the children with serious bacterial infections had the appropriate test (urine culture, chest radiograph, or blood culture). Antibiotics were prescribed acutely in 66% (359/543) of children with urinary tract infection, 69% (366/533) with pneumonia, and 81% (52/64) with bacteraemia. However, 20% (2686/13 557) of children without bacterial infection were also prescribed antibiotics. On the basis of the data from the clinical evaluations and the confirmed diagnosis, a diagnostic model was developed using multinomial logistic regression methods. Physicians' diagnoses of bacterial infection had low sensitivity (10-50%) and high specificity (90-100%), whereas the clinical diagnostic model provided a broad range of values for sensitivity and specificity.

CONCLUSIONS

Emergency department physicians tend to underestimate the likelihood of serious bacterial infection in young children with fever, leading to undertreatment with antibiotics. A clinical diagnostic model could improve decision making by increasing sensitivity for detecting serious bacterial infection, thereby improving early treatment.

Psychosocial outcomes of three triage methods for the management of borderline abnormal cervical smears: an open randomised trial

OBJECTIVE

To assess which of three triage strategies for women with borderline abnormal cervical smear results in the best psychosocial outcomes.

DESIGN

Pragmatic, non-blinded, multicentre, randomised controlled trial.

SETTING

18 family planning clinics across Australia, covering both urban and rural areas, between January 2004 and October 2006.

PARTICIPANTS

Women aged 16-70 years (n=314) who attended routine cervical screening and received a borderline cervical smear.

INTERVENTIONS

Patients were randomly assigned to human papillomavirus (HPV) DNA testing (n=104), a repeat smear test at six months (n=106), or the patient's informed choice of either test supported by a decision aid (n=104). Psychosocial outcomes were assessed at multiple time points over 12 months by postal questionnaire.

MAIN OUTCOME MEASURES

We assessed health related quality of life (SF36 mental health subscale), cognitive effects (such as perceived risk of cervical cancer, intrusive thoughts), affective outcomes (general anxiety [state-trait anxiety inventory]), specific anxiety about an abnormal smear (cervical screening questionnaire), and behavioural outcomes (sexual health behaviour and visits to the doctor) over 12 months of follow-up.

RESULTS

At two weeks, some psychosocial outcomes were worse for women allocated to HPV testing compared with those in the smear testing group (SF36 vitality subscale: t=-1.63, df=131, P=0.10; intrusive thoughts chi(2)=8.14, df=1, P<0.01). Over 12 months, distress about the abnormal smear was lowest in women allocated to HPV testing and highest in the repeat smear testing group (t=-2.89, df=135, P<0.01). Intrusive thoughts were highest in patients allocated to HPV testing (25%, compared with 13% in the informed choice group; difference=12%, 95% CI -1.1% to 25.1%). Women in the HPV DNA group and the informed choice group were more satisfied with their care than women allocated to repeat smear testing.

CONCLUSIONS

Although the psychosocial effect was initially worse for women allocated to HPV triage, over the full year of follow-up this intervention was better for women's psychosocial health than repeat smear testing. Offering informed choice could have a small advantage for cognitive outcomes, but in view of the additional effort and logistical complexity that this intervention requires, HPV testing alone can be justified for most women.

TRIAL REGISTRATION

actr.org.au Identifier: 12605000111673.

A randomised trial of general practitioner-written invitations to encourage attendance at screening mammography

The aim of this study was to examine the effectiveness of general practitioner-written invitations to the Breast X-Ray Programme of the Central Sydney Area Health Service. Five out of six randomly selected general practices in Drummoyne participated. Within each practice, women aged 45 to 70 were individually randomised to receive or not receive a letter from their general practitioner (GP). Thirty-two per cent of women attended if invited compared to 7 per cent if they were not sent an invitation. An attendance of 38 per cent was obtained for women whose GP chose to send a letter with an appointment compared to 24 per cent for women whose GP chose to send a general invitation without an appointment. Combining all practices, women who consulted their GP within the previous 6 months were more likely to attend in response to the invitation (38 per cent) than women whose last consultation was more remote, dropping to 15 per cent in those who last attended that GP over 2 years earlier. Women aged 65 to 70 years old were at least as likely to respond to the invitation as women aged 45 to 64. Reminder letters were subsequently sent to a random half of nonrespondents who had attended the practice in the previous 12 months. A further 18 per cent of women attended after the reminder letter was sent (8/45), compared with 2 per cent in the control group (1/48). Twenty-seven per cent of women in Drummoyne had already attended for screening mammography before the trial.(ABSTRACT TRUNCATED AT 250 WORDS)

Appropriate statistical methods are required to assess diagnostic tests for replacement, add-on, and triage

OBJECTIVE

To explain which measures of accuracy and which statistical methods should be used in studies to assess the value of a new binary test as a replacement test, an add-on test, or a triage test.

STUDY DESIGN AND SETTING

Selection and explanation of statistical methods, illustrated with examples.

RESULTS

Statistical methods for comparative diagnostic accuracy studies are described that take into account the purpose of the new diagnostic test. Methods are described within a framework that defines the major purpose of test comparison: assessing the value of a new test as a replacement test, an add-on test, or a triage test. Methods appropriate for both unpaired and paired study designs for binary test data are given, including regression modeling of diagnostic test accuracy. Implications for efficient study designs are also discussed.

CONCLUSIONS

Appropriate selection of existing statistical methods is necessary to address research questions about the comparative accuracy of new tests.

Prediction of incident stroke events based on retinal vessel caliber: a systematic review and individual-participant meta-analysis

The caliber of the retinal vessels has been shown to be associated with stroke events. However, the consistency and magnitude of association, and the changes in predicted risk independent of traditional risk factors, are unclear. To determine the association between retinal vessel caliber and the risk of stroke events, the investigators combined individual data from 20,798 people, who were free of stroke at baseline, in 6 cohort studies identified from a search of the Medline (National Library of Medicine, Bethesda, Maryland) and EMBASE (Elsevier B.V., Amsterdam, the Netherlands) databases. During follow-up of 5-12 years, 945 (4.5%) incident stroke events were recorded. Wider retinal venular caliber predicted stroke (pooled hazard ratio = 1.15, 95% confidence interval: 1.05, 1.25 per 20-micron increase in caliber), but the caliber of retinal arterioles was not associated with stroke (pooled hazard ratio = 1.00, 95% confidence interval: 0.92, 1.08). There was weak evidence of heterogeneity in the hazard ratio for retinal venular caliber, which may be attributable to differences in follow-up strategies across studies. Inclusion of retinal venular caliber in prediction models containing traditional stroke risk factors reassigned 10.1% of people at intermediate risk into different, mostly lower, risk categories.

Estimates of overdiagnosis of invasive breast cancer associated with screening mammography

PURPOSE

To estimate the extent of overdiagnosis of invasive breast cancer associated with screening in New South Wales, Australia, a population with a well-established mammography screening program which has achieved full geographic coverage.

METHODS

We calculated overdiagnosis as the observed annual incidence of invasive breast cancer in NSW in 1999-2001 (a screened population) minus the expected annual incidence in this population at the same time, as a percentage of the expected incidence. We estimated expected incidence without screening in 1999-2001 from the incidence of invasive breast cancer in: (1) women in unscreened age groups (interpolation method); and (2) women in all age groups prior to the implementation of screening (extrapolation method). We then adjusted these estimates for trends in major risk factors for breast cancer that may have coincided with the introduction of mammography screening: increasing obesity, use of hormone replacement therapy (HRT) and nulliparity. Finally, we adjusted for lead time to produce estimates of expected incidence in 1999-2001. These were compared with the observed incidence in 1999-2001 to calculate overdiagnosis of breast cancer associated with screening.

RESULTS

Overdiagnosis of invasive breast cancer among 50-69 year NSW women was estimated to be 42 and 30% using the interpolation and extrapolation methods, respectively.

CONCLUSION

Overdiagnosis of invasive breast cancer attributable to mammography screening appears to be substantial. Our estimates are similar to recent estimates from other screening programmes. Overdiagnosis merits greater attention in research and in clinical and public health policy making.

Does providing previous results change the accuracy of cervical cytology?

OBJECTIVE

To determine whether providing previous cytology and histology findings alters the accuracy of conventional cervical cytology reading or changes reading times.

STUDY DESIGN

Each of 9 cytologists read 9 batches of 8 routinely referred Pap smears (total, 648 slides), with history (H) and without history (NH), at an interval of no less than 4 weeks. Each batch was read blind to the result of reading under the other strategy and to histology. Histologic cervical intraepithelial neoplasia 2 or more severe was the reference standard. Accuracy of reading was assessed across all thresholds using receiver operating characteristic (ROC) curves and by sensitivity and specificity at a cytology threshold of possible low grade squamous intraepithelial lesion (consistent with atypical squamous cells of undermined significance).

RESULTS

Areas under the ROC curve, sensitivities and specificities were similar if read with or without history, except for 1 reader for whom reading with history increased the area under the ROC curve from 0.716 to 0.833 (increase of 0.117, p = 0.017) and the sensitivity from 0.57 to 0.79 (increase of 0.22, p = 0.014), without any significant change in specificity. Accuracy varied between subgroups defined by age and by the severity and timing of previous abnormalities, but the results of the comparison of accuracy in H and NH did not vary by subgroup. Mean reading times were 8.2 (H) and 7.9 (NH) minutes per slide, a difference of 0.34 minutes (p = 0.083). Differences in mean batch times (H-NH) between readers ranged from -0.08 to 1.0 minutes, the largest difference being for the reader whose accuracy increased.

CONCLUSION

An accurate history might improve accuracy for some cytologists.

Magnetic resonance imaging screening of the contralateral breast in women with newly diagnosed breast cancer: systematic review and meta-analysis of incremental cancer detection and impact on surgical management

PURPOSE

Preoperative magnetic resonance imaging (MRI) is increasingly used for staging women with breast cancer, including screening for occult contralateral cancer. This article is a review and meta-analysis of studies reporting contralateral MRI in women with newly diagnosed invasive breast cancer.

METHODS

We systematically reviewed the evidence on contralateral MRI, calculating pooled estimates for positive predictive value (PPV), true-positive:false-positive ratio (TP:FP), and incremental cancer detection rate (ICDR) over conventional imaging. Random effects logistic regression examined whether estimates were associated with study quality or clinical variables.

RESULTS

Twenty-two studies reported contralateral malignancies detected only by MRI in 131 of 3,253 women. Summary estimates were as follows: MRI-detected suspicious findings (TP plus FP), 9.3% (95% CI, 5.8% to 14.7%); ICDR, 4.1% (95% CI, 2.7% to 6.0%), PPV, 47.9% (95% CI, 31.8% to 64.6%); TP:FP ratio, 0.92 (95% CI, 0.47 to 1.82). PPV was associated with the number of test positives and baseline imaging. Few studies included consecutive women, and few ascertained outcomes in all subjects. Where reported, 35.1% of MRI-detected cancers were ductal carcinoma in situ (mean size = 6.9 mm), 64.9% were invasive cancers (mean size = 9.3 mm), and the majority were stage pTis or pT1 and node negative. Effect on treatment was inconsistently reported, but many women underwent contralateral mastectomy.

CONCLUSION

MRI detects contralateral lesions in a substantial proportion of women, but does not reliably distinguish benign from malignant findings. Relatively high ICDR may be due to selection bias and/or overdetection. Women must be informed of the uncertain benefit and potential harm, including additional investigations and surgery.

Using the Principles of Randomized Controlled Trial Design to Guide Test Evaluation

The decision to use a new test should be based on evidence that it will improve patient outcomes or produce other benefits without adversely affecting patients. In principle, long-term randomized controlled trials (RCTs) of test-plus-treatment strategies offer ideal evidence of the benefits of introducing a new test relative to current best practice. However, long-term RCTs may not always be necessary. The authors advocate using the hypothetical RCT as a conceptual framework to identify what types of comparative evidence are needed for test evaluation. Evaluation begins by stating the major claims for the new test and determining whether it will be used as a replacement, add-on, or triage test to achieve these claims. A flow diagram of this hypothetical RCT is constructed to show the essential design elements, including population, prior tests, new test and existing test strategies, and primary and secondary outcomes. Critical steps in the pathway between testing and patient outcomes, such as differences in test accuracy, changes in treatment, or avoidance of other tests, are displayed for each test strategy. All differences between the tests at these critical steps are identified and prioritized to determine the most important questions for evaluation. Long-term RCTs will not be necessary if it is valid to use other sources of evidence to address these questions. Validity will depend on issues such as the spectrum of patients identified by the old and new test strategies.

Meta-analysis: retinal vessel caliber and risk for coronary heart disease

BACKGROUND

Retinal vessel caliber may be a novel marker of coronary heart disease (CHD) risk. However, the sex-specific effect, magnitude of association, and effect independent of traditional CHD disease risk factors remain unclear.

PURPOSE

To determine the association between retinal vessel caliber and risk for CHD.

DATA SOURCES

Relevant studies in any language identified through MEDLINE (1950 to June 2009) and EMBASE (1950 to June 2009) databases.

STUDY SELECTION

Studies were included if they examined a general population, measured retinal vessel caliber from retinal photographs, and documented CHD risk factors and incident CHD events.

DATA EXTRACTION

6 population-based prospective cohort studies provided data for individual participant meta-analysis.

DATA SYNTHESIS

Proportional hazards models, adjusted for traditional CHD risk factors, were constructed for retinal vessel caliber and incident CHD in women and men. Among 22,159 participants who were free of CHD and followed for 5 to 14 years, 2219 (10.0%) incident CHD events occurred. Retinal vessel caliber changes (wider venules and narrower arterioles) were each associated with an increased risk for CHD in women (pooled multivariable-adjusted hazard ratios, 1.16 [95% CI, 1.06 to 1.26] per 20-microm increase in venular caliber and 1.17 [CI, 1.07 to 1.28] per 20-microm decrease in arteriolar caliber) but not in men (1.02 [CI, 0.94 to 1.10] per 20-microm increase in venular caliber and 1.02 [CI, 0.95 to 1.10] per 20-microm decrease in arteriolar caliber). Women without hypertension or diabetes had higher hazard ratios.

LIMITATION

Error in the measurement of retinal vessel caliber and Framingham variables was not taken into account.

CONCLUSION

Retinal vessel caliber changes were independently associated with an increased risk for CHD events in women.

Value of routine monitoring of bone mineral density after starting bisphosphonate treatment: secondary analysis of trial data

OBJECTIVE

To assess the value of monitoring response to bisphosphonate treatment by means of measuring bone mineral density.

DESIGN

Secondary analysis of trial data using mixed models. Data source The Fracture Intervention Trial, a randomised controlled trial that compared the effects of alendronate and placebo in 6459 postmenopausal women with low bone mineral density recruited between May 1992 and May 1993. Bone density measurements of hip and spine were obtained at baseline and at one, two, and three years after randomisation.

MAIN OUTCOME MEASURES

Between-person (treatment related) variation and within-person (measurement related) variation in hip and spine bone mineral density.

RESULTS

The mean effect of three years' treatment with alendronate was to increase hip bone mineral density by 0.030 g/cm(2). There was some between-person variation in the effects of alendronate, but this was small in size compared with within-person variation. Alendronate treatment is estimated to result in increases in hip bone density >or=0.019 g/cm(2) in 97.5% of patients.

CONCLUSIONS

Monitoring bone mineral density in postmenopausal women in the first three years after starting treatment with a potent bisphosphonate is unnecessary and may be misleading. Routine monitoring should be avoided in this early period after bisphosphonate treatment is commenced.

Long term monitoring in patients receiving treatment to lower blood pressure: analysis of data from placebo controlled randomised controlled trial

OBJECTIVE

To determine the value of monitoring blood pressure by quantifying the probability that observed changes in blood pressure reflect true changes.

DESIGN

Analysis of blood pressure measurements of patients in the perindopril protection against recurrent stroke study (PROGRESS).

SETTING

Randomised placebo controlled trial carried out in 172 centres in Asia, Australasia, and Europe.

PARTICIPANTS

1709 patients with history of stroke or transient ischaemic attack randomised to fixed doses of perindopril and indapamide. Measurements Mean of two blood pressure measurements in patients receiving treatment recorded to the nearest 2 mm Hg with a standard mercury sphygmomanometer at baseline and then at three months, six months, nine months, and 15 months and then every six months to 33 months.

RESULTS

There was no change in the mean blood pressure of the cohort during the 33 month follow-up. Six months after blood pressure was stabilised on treatment, if systolic blood pressure was measured as having increased by >10 mm Hg, six of those measurements would be false positives for every true increase of >or=10 mm Hg. The corresponding value for an increase of 20 mm Hg was over 200. Values for 5 mm Hg and 10 mm Hg increases in diastolic blood pressure were 3.5 and 39, respectively. The likelihood that observed increases in blood pressure reflected true increases rose with the time between measurements such that the ratio of true positives to false positives reached parity at 21 months.

CONCLUSIONS

Usual clinical approaches to the monitoring of patients taking drugs to lower blood pressure have a low probability of yielding reliable information about true changes in blood pressure. Evidence based guidelines for monitoring treatment response are urgently required to guide clinical practice. Trial registration Australia and New Zealand Clinical Trial Registry.

Mixed models showed no need for initial response monitoring after starting antihypertensive therapy

OBJECTIVE

To demonstrate how mixed models may be used to estimate treatment effects, and inform decisions on the need for monitoring initial response.

STUDY DESIGN AND SETTING

Mixed models were used to analyze data from the Perindopril Protection Against Recurrent Stroke Study (PROGRESS), which examined the effects of perindopril and indapamide in 6,105 patients at high risk of a cerebrovascular event.

RESULTS

The mean effect of perindopril was to lower blood pressure (BP) (systolic/diastolic) by 6/3 mmHg. The mean effects of perindopril/indapamide varied according to baseline BP, and lowering of BP ranged from 9/5 to 14/5 mmHg (for individuals with a baseline systolic BP <140 and >150 mmHg, respectively). We found no variation in the effects of treatment on BP for either perindopril alone or in combination with indapamide. The effects of treatment on the individual can be predicted from the mean effect of treatment for the group (perindopril) or baseline systolic BP subgroup (perindopril/indapamide).

CONCLUSION

Monitoring initial treatment response is unnecessary for antihypertensives similar to those examined in this study. To address this issue for other therapies, we suggest that trials should report estimates of treatment effects from mixed models, and the CONSORT statement should be expanded to include this item.

Assessing new biomarkers and predictive models for use in clinical practice: a clinician's guide

New biomarkers and predictive models that aim to improve the identification of people at risk of cardiovascular disease are constantly proposed. Clinicians need to be aware of the various methods used to assess these biomarkers and models and how these should be interpreted. New biomarkers and models are assessed in terms of their contribution to global fit, discrimination, calibration, and reclassification. These measures, when used in isolation, do not address the clinically important questions of whether the new model predicts risk more accurately than existing models and whether the risks predicted for individuals are sufficiently different to warrant a change in treatment decisions. We recommend that these measures be supplemented with graphical displays such as a calibration plot for the Hosmer-Lemeshow test and a scatterplot of the risks predicted by the models being compared. We encourage researchers to report such analyses from studies on the clinical utility of new biomarkers because this information is pertinent for the clinician who must decide whether to test for a new biomarker in their clinical practice.

When should a new test become the current reference standard?

The evaluation of claims that a new diagnostic test is better than the current gold standard test is hindered by the lack of a perfect reference judge. However, this problem may be sidestepped by focusing on the clinical consequences of the decision rather than on estimation of accuracy. Consequences can be assessed by use of a "fair umpire" test that is not perfect yet can discriminate between disease and nondisease cases and is not biased in favor of 1 test. This article discusses 3 principles to aid judgments about the value of new tests. First, the consequences are best examined in cases with disagreement between the current and new tests. Second, resolving these disagreements requires a fair, but not necessarily perfect, umpire test. Finally, umpire tests include consequences, such as prognosis and response to treatment, as well as causal exposures and other test results.

HPV testing versus repeat Pap testing for the management of a minor abnormal Pap smear: evaluation of a decision aid to support informed choice

OBJECTIVE

To examine women's informed preference for the management of a mildly abnormal Pap smear and the impact of a decision aid.

METHODS

Women (n=106) were given a choice of management supported by a decision aid and surveyed before, and after decision making to evaluate predictors of choice and decision aid impact.

RESULTS

HPV triage was preferred by most women (65%) although a substantial minority selected repeat Pap testing (35%). Women who chose HPV triage were more likely to have had children, have had a previous abnormal Pap smear and were more distressed than women who chose a repeat Pap test. In total, 68% of women made an informed choice. Rapid timing of follow-up was important for women choosing HPV testing. The lower chance of colposcopy and greater opportunity for regression, were rated as important by women choosing Pap testing. Decisional conflict was lower among women who chose HPV triage. No other differences in short-term psychological outcomes were found.

CONCLUSION

The decision aid supported informed choice among the majority of women. Women tailored their choice to their practical, health and psychological needs.

PRACTICE IMPLICATIONS

Offering women an informed choice for a mildly abnormal Pap smear may enable women to select the management that best suits their circumstances.

Diagnostic test accuracy may vary with prevalence: implications for evidence-based diagnosis

BACKGROUND

Several studies and systematic reviews have reported results that indicate that sensitivity and specificity may vary with prevalence.

STUDY DESIGN AND SETTING

We identify and explore mechanisms that may be responsible for sensitivity and specificity varying with prevalence and illustrate them with examples from the literature.

RESULTS

Clinical and artefactual variability may be responsible for changes in prevalence and accompanying changes in sensitivity and specificity. Clinical variability refers to differences in the clinical situation that may cause sensitivity and specificity to vary with prevalence. For example, a patient population with a higher disease prevalence may include more severely diseased patients, therefore, the test performs better in this population. Artefactual variability refers to effects on prevalence and accuracy associated with study design, for example, the verification of index test results by a reference standard. Changes in prevalence influence the extent of overestimation due to imperfect reference standard classification.

CONCLUSIONS

Sensitivity and specificity may vary in different clinical populations, and prevalence is a marker for such differences. Clinicians are advised to base their decisions on studies that most closely match their own clinical situation, using prevalence to guide the detection of differences in study population or study design.

Risk prediction of coronary heart disease based on retinal vascular caliber (from the Atherosclerosis Risk In Communities [ARIC] Study)

Recent studies showed that such retinal vascular signs as quantitative retinal vascular caliber were associated with increased risk of incident coronary heart disease (CHD), but whether these retinal vascular signs add to the prediction of CHD over and above traditional CHD risk factors was not addressed. Whether these signs add to the prediction of CHD over and above the Framingham risk score in people (n = 9,155) without diabetes selected from the ARIC Study was investigated. Incident CHD was ascertained using standardized methods, and retinal vascular caliber and other retinal signs were measured from retinal photographs. After a mean of 8.8 years of follow-up, there were 700 incident CHD events. Women with wider retinal venular caliber (hazard ratio 1.27/1-SD increase, 95% confidence interval 1.08 to 1.50) and narrower retinal arteriolar caliber (hazard ratio 1.31/1-SD decrease, 95% confidence interval 1.10 to 1.56) had a higher risk of incident CHD after adjusting for Framingham risk score variables. Area under the receiver operator characteristic curve increased from 0.695 to 0.706 (1.7% increase) with the addition of retinal vascular caliber to the Framingham risk model. Risk prediction models with and without retinal vascular caliber both fitted the data and were well calibrated for women. In men, retinal vascular caliber was not associated with CHD risk after adjustment. Other retinal vascular signs were not associated with 10-year incident CHD in men or women. In conclusion, although retinal vascular caliber independently predicted CHD risk in women, the incremental predictive ability over that of the Framingham model was modest and unlikely to translate meaningfully into clinical practice.

Cochrane systematic review of colorectal cancer screening using the fecal occult blood test (hemoccult): an update

BACKGROUND AND AIMS

Reducing mortality from colorectal cancer (CRC) may be achieved by the introduction of population-based screening programs. The aim of the systematic review was to update previous research to determine whether screening for CRC using the fecal occult blood test (FOBT) reduces CRC mortality and to consider the benefits, harms, and potential consequences of screening.

METHODS

We searched eight electronic databases (Cochrane Library, MEDLINE, EMBASE, CINAHL, PsychINFO, AMED, SIGLE, and HMIC). We identified nine articles describing four randomized controlled trials (RCTs) involving over 320,000 participants with follow-up ranging from 8 to 18 yr. The primary analyses used intention to screen and a secondary analysis adjusted for nonattendance. We calculated the relative risks and risk differences for each trial, and then overall, using fixed and random effects models.

RESULTS

Combined results from the four eligible RCTs indicated that screening had a 16% reduction in the relative risk (RR) of CRC mortality (RR 0.84, 95% confidence interval [CI] 0.78-0.90). There was a 15% RR reduction (RR 0.85, 95% CI 0.78-0.92) in CRC mortality for studies that used biennial screening. When adjusted for screening attendance in the individual studies, there was a 25% RR reduction (RR 0.75, 95% CI 0.66-0.84) for those attending at least one round of screening using the FOBT. There was no difference in all-cause mortality (RR 1.00, 95% CI 0.99-1.02) or all-cause mortality excluding CRC (RR 1.01, 95% CI 1.00-1.03).

CONCLUSIONS

The present review includes seven new publications and unpublished data concerning CRC screening using FOBT. This review confirms previous research demonstrating that FOBT screening reduces the risk of CRC mortality. The results also indicate that there is no difference in all-cause mortality between the screened and nonscreened populations.

Randomized trial of a self-administered decision aid for colorectal cancer screening

Objective

Previous studies have not assessed whether evidence-based information about the outcomes of colorectal cancer screening increases informed choice among people from a range of socioeconomic backgrounds nor have they assessed whether this can be administered away from a health-care provider.

Methods

Randomized controlled trial in six primary care locations. Three hundred and fourteen people aged 50–74 years received a self-administered decision aid (DA) booklet about outcomes of biennial faecal occult blood testing (FOBT) screening or government consumer guidelines (G).

Results

Significantly more DA recipients (20.9%) were ‘informed’ compared with G recipients (5.8%) ( P = 0.0001, OR 4.32; 95% CI 2.49 to 7.52); the DA did not affect values clarity (61.9% clear after DA versus 59.1% after G) nor screening decisions overall (87.3% would screen after DA versus 90.5% after G). Test uptake at one month was uniformly low (5.2% DA versus 6.6% G); mostly due to being ‘too busy’. DA recipients were more likely to make decisions ‘integrating’ knowledge with values (10.4% DA versus 1.5% G). Decisions not to screen were equally uncommon in both groups but more likely to be uninformed in G ( P = 0.03). More DA recipients from all education levels were ‘informed’ ( P = 0.02), particularly in lower education (50.0% DA versus 17.8% G) and university-educated groups (79.4% DA versus 32.1% G).

Conclusion

Detailed absolute risk and benefit information about FOBT screening can be effectively used at home by people to increase informed choice. The DA was effective in people with lower education levels.

Trial Registration

Unique Protocol ID 211705 ClinicalTrials.gov ID NCT 00148226.

Accuracy and surgical impact of magnetic resonance imaging in breast cancer staging: systematic review and meta-analysis in detection of multifocal and multicentric cancer

PURPOSE We review the evidence on magnetic resonance imaging (MRI) in staging the affected breast to determine its accuracy and impact on treatment. METHODS Systematic review and meta-analysis of the accuracy of MRI in detection of multifocal (MF) and/or multicentric (MC) cancer not identified on conventional imaging. We estimated summary receiver operating characteristic curves, positive predictive value (PPV), true-positive (TP) to false positive (FP) ratio, and examined their variability according to quality criteria. Pooled estimates of the proportion of women whose surgery was altered were calculated. Results Data from 19 studies showed MRI detects additional disease in 16% of women with breast cancer (N = 2,610). MRI incremental accuracy differed according to the reference standard (RS; P = .016) decreasing from 99% to 86% as the quality of the RS increased. Summary PPV was 66% (95% CI, 52% to 77%) and TP:FP ratio was 1.91 (95% CI, 1.09 to 3.34). Conversion from wide local excision (WLE) to mastectomy was 8.1% (95% CI, 5.9 to 11.3), from WLE to more extensive surgery was 11.3% in MF/MC disease (95% CI, 6.8 to 18.3). Due to MRI-detected lesions (in women who did not have additional malignancy on histology) conversion from WLE to mastectomy was 1.1% (95% CI, 0.3 to 3.6) and from WLE to more extensive surgery was 5.5% (95% CI, 3.1 to 9.5). CONCLUSION MRI staging causes more extensive breast surgery in an important proportion of women by identifying additional cancer, however there is a need to reduce FP MRI detection. Randomized trials are needed to determine the clinical value of detecting additional disease which changes surgical treatment in women with apparently localized breast cancer.