SUMMARY. Studies of the effectiveness of various strategies for influencing clinicians' test-requesting behaviour are reviewed. Numerical rationing. although crude. effectively reduces unnecessary repeat testing without detriment to patient outcome. Educational programmes involving peer review show pronounced but short-lived effects. Simple feedback of information about numbers of tests requested and their costs is surprisingly ineffectual. Direct financial incentives. in a private health care system. also failed. Clinical budgeting. of benefit in experimental trials. has yet to be widely tested. and the savings on reducing laboratory requesting may not be large enough to be attractive to clinicians. Agreed requesting policies in various specialities and clinical circumstances. endorsed by senior clinicians and prestigious professional bodies. seems a promising approach to more appropriate test requesting; further objective studies of their long-term effects are needed. Redesign of request forms into a problem-orientated format may be the simplest and most effective contribution by the laboratory; this strategy deserves further critical appraisal.The ever-increasing costs of health care are of worldwide concern. Hospital-based services consume a large part of such costs. and excessive clinical laboratory testing is often thought to be a major contribution to the problemalthough with laboratory expenditure running at less than 4% of the total hospital expenditure in the UK.' it is hard to see why. In contrast, in the USA. at least up until the introduction of prospective reimbursement based on diagnosis-related groups, 25% of the patient's bill might consist of the charges for diagnostic investigations."Those who seek ways to economise have tended to seize on pathology and imaging departments as potential objects of cost-cutting exercises partly because their costs are identifi- able and easily quantified. but also because it is evident that the easy availability of apparently cheap tests has frequently led to excessive, unnecessary requesting: it is a reasonable deduction. then, that sizeable economies could be effected here without detriment to health care. There is much evidence to support such a view in the several publications of laboratory scientists and clinicians which point to examples of excessive, inappropriate or unnecessary test requesting (references 3-8, to name but a few).We believe that the exclusive emphasis on cost containment is misplaced. Attention should be focused not on merely reducing the numbers of tests requested, but on reducing the amount of inappropriate testing. Clinicians and laboratory scientists may differ substantially') on the amount of testing they consider necessary; they will. however, more readily agree that inappropriate (including excessive) requesting could lead to harmful further diagnostic investigation, needlessly prolonged hospital stay. poor understanding of results and incorrect action. or even to iatrogenic disorder attributable to 'treating the biochemistry' rath...
