Number needed to screen: development of a statistic for disease screening

Rembold, Christopher M.

doi:10.1136/bmj.317.7154.307

Cited by 324 publications

(235 citation statements)

References 22 publications

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“…5 In our study, however, values of the NNS for an individual decrease in %DLCO every 3 and 6 months seem not to be high from the viewpoints of prevention and early detection of APT, because these values are lower than those for mammography in women aged 50-59. 31 KL-6 is a high-molecular-weight, mucin-like glycoprotein secreted by proliferating type II alveolar pneumocytes, and is a sensitive marker of disease activity in various interstitial lung diseases. 32 An increase in the level of circulating KL-6 has been described in APT patients, 7 but its sensitivity and specificity as a predictor of APT are unclear.…”

Section: Discussionmentioning

confidence: 99%

Incidence and Predictors of Pulmonary Toxicity in Japanese Patients Receiving Low-Dose Amiodarone

Yamada

Shiga

Matsuda

et al. 2007

Circ J

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Background Amiodarone-induced pulmonary toxicity (APT) is the most serious side-effect of amiodarone, and its detection and prevention are extremely important. This study was designed to evaluate the incidence and clinical risk factors of APT, and the utility of a pulmonary function test or serum KL-6 assay to predict pulmonary toxicity in Japanese patients receiving low-dose amiodarone. Methods and ResultsFive hundred consecutive patients receiving amiodarone were retrospectively evaluated. Mean follow-up period was 48 months and mean maintenance dose was 141 mg daily. Cumulative incidence of APT was 4.2%, 7.8%, and 10.6% at 1, 3, and 5 years, respectively. On multivariate analysis, age at the start (hazard ratio (HR) =1.48, 95% confidence interval (CI) 1.13 to 1.93) was a significant pretreatment risk factor. Age (HR =1.64, 95% CI 1.29 to 2.09), maintenance dose (HR =1.90, 95% CI 1.45 to 2.49) and plasma monodesethylamiodarone concentration (HR =1.30, 95%CI 1.08 to 1.58) were risk factors. Sensitivity and specificity in screening with measurement of percent predicted diffusion capacity of carbon monoxide, ≥15% individual decrease, were 68% and 69%, and for ≥20% individual decrease, were 59% and 74%, whereas those in screening with serum KL-6 assay, ≥500 U/ml, were 25% and 91%, respectively. Conclusions Even at low dose, amiodarone shows substantial pulmonary toxicity. Higher age and higher maintenance dose are risk factors. Further decreasing the maintenance dose of amiodarone should be considered in order to reduce the incidence of pulmonary toxicity, at least in Japanese patients. (Circ J 2007; 71: 1610 -1616

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Section: Discussionmentioning

confidence: 99%

Incidence and Predictors of Pulmonary Toxicity in Japanese Patients Receiving Low-Dose Amiodarone

Yamada

Shiga

Matsuda

et al. 2007

Circ J

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“…This concept has been statistically described [14] and used in studies with radiographic assessment of different diseases, presented according to Number Needed to Treat (NNT) analysis terminology [15]. With the clear similarities between radiological and clinical screening, we suggest that the use of NNS is appropriate in the present clinical trial.…”

Section: Number Needed To Screen (Nns) and Number Needed To Allocatementioning

confidence: 99%

The challenge of recruiting patients with anterior cruciate ligament injury of the knee into a randomized clinical trial comparing surgical and non-surgical treatment

Frobell

Lohmander

Roos

2007

Contemporary Clinical Trials

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This is an author produced version of a paper published Contemporary clinical trials. This paper has been peerreviewed but does not include the final publisher proofcorrections or journal pagination. 2 AbstractAims --To determine the number of patients needed to be screened (NNS) and allocated (NNA) to include one participant into a randomized clinical trial (RCT), and to compare the characteristics of patients accepting or declining participation in the RCT.Methods --The recruitment process of an ongoing multicenter RCT, comparing surgical and nonsurgical interventions after acute anterior cruciate ligament (ACL) injury of the knee is described. We use the known concept Number Needed to Screen (NNS) and introduce the new concept NumberNeeded to Allocate (NNA) as variables to support a priori sample size calculations of future investigations.Results --560 patients were screened to identify 162 patients (29%) eligible for inclusion in the RCT. 41of those declined participation for various reasons, the most common being unwillingness to undergo surgery (n=23) or unwillingness to risk conservative treatment (n=8). 19 patients were excluded after MRI assessment or arthroscopy. Thus, 102 (18%) patients were allocated to one of the two treatments in the RCT. The NNS was 5.5 individuals with an acute knee injury, and the NNA was 1.6 individuals eligible for inclusion, to include 1 patient in the RCT. Patients declining to participate in the RCT were more frequently self-employed and less frequently injured in sports activities than those accepting RCT participation.Conclusions --We suggest that the a priori sample size calculation needs to be multiplied by at least 5.5to provide an estimate of the number needed to screen, or 1.6 to provide an estimate of the number needed to allocate in order to include the desired number of patients in a trial comparing surgical and non-surgical treatment of the ACL injured patient.

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“…25 Another absolute measure of benefit is the number needed to screen (NNS), which describes how many people have to be screened and provided follow-up testing and treatment to save one person (a slightly modified form of the number needed to treat (NNT) measure). 26 According to the model above, roughly 204 women have to be screened for 20 years to save one from dying of breast cancer during that time period. 25 However, patients are rarely given such absolute measures of possible benefit.…”

Section: Patient Understanding and Framing Of Risk/ Benefit Datamentioning

confidence: 99%

The Ethics of Information: Absolute Risk Reduction and Patient Understanding of Screening

Schwartz

Meslin

2008

J GEN INTERN MED

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Number needed to screen: development of a statistic for disease screening

Cited by 324 publications

References 22 publications

Incidence and Predictors of Pulmonary Toxicity in Japanese Patients Receiving Low-Dose Amiodarone

Incidence and Predictors of Pulmonary Toxicity in Japanese Patients Receiving Low-Dose Amiodarone

The challenge of recruiting patients with anterior cruciate ligament injury of the knee into a randomized clinical trial comparing surgical and non-surgical treatment

The Ethics of Information: Absolute Risk Reduction and Patient Understanding of Screening

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