Methods for evaluating area-wide and organisation-based interventions in health and health care: a systematic review.

Abstract

T he overall aim of the NHS R&D Health Technology Assessment (HTA) programme is to ensure that high-quality research information on the costs, effectiveness and broader impact of health technologies is produced in the most efficient way for those who use, manage and work in the NHS. Research is undertaken in those areas where the evidence will lead to the greatest benefits to patients, either through improved patient outcomes or the most efficient use of NHS resources. The Standing Group on Health Technology advises on national priorities for health technology assessment. Six advisory panels assist the Standing Group in identifying and prioritising projects. These priorities are then considered by the HTA Commissioning Board supported by the National Coordinating Centre for HTA (NCCHTA). This report is one of a series covering acute care, diagnostics and imaging, methodology, pharmaceuticals, population screening, and primary and community care. It was identified as a priority by the Methodology Panel and funded as project number 94/09/01. The views expressed in this publication are those of the authors and not necessarily those of the Standing Group, the Commissioning Board, the Panel members or the Department of Health. The editors wish to emphasise that funding and publication of this research by the NHS should not be taken as implicit support for the recommendations for policy contained herein. In particular, policy options in the area of screening will be considered by the National Screening Committee. This Committee, chaired by the Chief Medical Officer, will take into account the views expressed here, further available evidence and other relevant considerations. Reviews in Health Technology Assessment are termed 'systematic' when the account of the search, appraisal and synthesis methods (to minimise biases and random errors) would, in theory, permit the replication of the review by others.

Continuous quality improvement: effects on professional practice and healthcare outcomes

“…Standard statistical methods assume independence of observations, and their use in these types of studies will generally result in artificially small P values and overly narrow confidence intervals for the effect estimates (Ukoumunne 1999). These studies can generally be re-analysed by making assumptions about the intra-cluster correlation (ICC).…”

“…These studies can generally be re-analysed by making assumptions about the intra-cluster correlation (ICC). Estimates of ICC will be obtained from contacting authors, or imputed, using external estimates from similar studies (Ukoumunne 1999;Health Services Research Unit) or using general recommendations from empirical research (Campbell 2000). If this is not possible we will report the effect estimate and annotate the phrase 'unit of analysis error'.…”

Unequal cluster sizes for trials in English and Welsh general practice: implications for sample size calculations

“…The intracluster correlation coe cients chosen here are based on actual studies in general practice but may be higher than average [19]. Two di erent types of outcome have been illustrated, both common in general practice cluster trials: a patient outcome in the injury trial and a process of care outcome in the chlamydia trial.…”

Sample size calculations for intervention trials in primary care randomizing by primary care group: an empirical illustration from one proposed intervention trial

“…The absolute decrease in ICC is about the same between local authorities and health authorities (ratio of average cluster sizes approximately 4 : 1) as it is between health authorities and regions (ratio of average cluster sizes approximately 13 : 1). Although analysis of variance produces an e cient point estimate of the intracluster correlation coe cient for dichotomous outcomes such as ours, it is not an appropriate method for estimating corresponding conÿdence limits [16]. This is an area that is beginning to be explored [17] but still requires more investigation.…”