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Targeted screening of particular groups for open angle glaucoma would be more cost effective than testing the general population, a UK modelling study concludes.
The study compared different strategies for screening for open angle glaucoma (the commonest type of glaucoma, which is the leading cause of irreversible blindness) by reviewing the existing research evidence for effectiveness and cost effectiveness.
One strategy was for a glaucoma screening technician to measure intraocular pressure and then do a second test from a range of possible tests to screen people considered to be at risk of open angle glaucoma. The United Kingdom doesn't currently have glaucoma screening technicians, but the researchers assumed that staff could be trained and accredited in a similar way to retinal screening technicians who screen for diabetic retinopathy.
A second potential strategy—which costs more—involved patients at high risk being invited to be assessed by a glaucoma optometrist.
Positive results of screening in either strategy would result in the patient being referred for diagnosis by an ophthalmologist, as occurs currently.
The researchers, who were asked to carry out the study by the National Institute for Health Research as part of its health technology assessment programme, used figures on costs and effectiveness from systematic reviews of the literature to model the two new potential screening strategies.
Their results show that initial testing of high risk people by a technician was more cost effective than patients being seen by a glaucoma optometrist straight away. Both strategies were more cost effective than screening the general population. However, cost effectiveness was highly sensitive to which costs were considered, whether those to the NHS alone or the costs of blindness to society.
The model showed that screening detected more cases of glaucoma than the current strategy of opportunistic detection by opticians but at the expense of a higher number of false positive results. The authors estimated that the prevalence of glaucoma would have to be 4% for a screening programme starting at the age of 50 to approach £30000 (€42000; $62000) per quality adjusted life year (QALY) gained, an amount that might be considered cost effective. This would mean screening only people with additional risk factors for glaucoma—about 6% of the eligible age group.
Overall the findings indicate that screening the general population for open angle glaucoma would not be cost effective and would not meet the criteria set down by the UK National Screening Committee, the body that advises the NHS on screening policy.
Jennifer Burr, clinical epidemiologist at the University of Aberdeen's Health Services Research Unit and the study's lead author, said, “Population screening is not likely to be cost effective, but targeted screening of high risk groups may be. Measures to systematically identify those at risk and quality assure the programme would be required.”
She added, “Many cases of open angle glaucoma are undetected, and there are a number of people who are more at risk of the condition than others, such as those with a first degree relative with glaucoma or those of black ethnicity. In the first year of screening the technician screening strategy would detect approximately 600 more previously undetected cases of glaucoma in these high risk groups at first screening than the current opportunistic approach.”
The Clinical Effectiveness and Cost-effectiveness of Screening for Open Angle Glaucoma: A Systematic Review and Economic Evaluation is at www.hta.ac.uk/project/1446.asp.