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The magnitude of treatment effect from randomized controlled trials can be measured in various ways. The number needed to treat is a recently described measure that has been shown to offer several advantages in the clinical interpretation and application of reported treatment effects. It quantifies the number of patients that must be treated in order to prevent one patient from developing the specified outcome. The methods necessary to calculate traditional measures of treatment effect, as well as the number needed to treat, are outlined using the management of diabetic retinopathy as an example. The uses and limitations of the number needed to treat are also discussed. [ABSTRACT FROM AUTHOR]

Objective:To evaluate two photoscreeners in a childhood population. Study design:Double-masked study. Subjects and method:One hundred and thirteen children aged between 11 and 44 months with either normal vision or known visual disorders were photoscreened without cycloplegia by the Otago and Dortmans (prototype) photoscreeners. Each child had a full ophthalmological examination either on the day of screening or in the preceeding six months. Photoscreen images were reviewed by an independent observer for indicators of amblyopiogenic risk factors, and compared to the full ophthalmological examination to determine sensitivity and specificity for each instrument. Results:The Otago photoscreener returned a sensitivity of 70% and specificity of 82% for the detection of amblyopiogenic risk factors. The Dortmans photoscreener returned a sensitivity of 70% and specificity of 90%. Both photoscreeners were portable and easily operated. Conclusion: Children can be screened successfully for amblyopiogenic risk factors with these photoscreening systems. Further evaluation is required to determine specificity in a normal population. This would also provide information on the potential usefulness of photoscreeners in a cost effective childhood vision screening program. [ABSTRACT FROM AUTHOR]