Screening again

The issue about whether tests are needed has hit the news again with the campaign to reduce the harmful effects of too much medicine.

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Author: Dr Susan Blakeney FCOptom, Clinical Adviser
Date: 26 May 2015

Following on from my last Clinical Notes column on screening, the issue about whether tests are needed has hit the news again with the campaign to reduce the harmful effects of too much medicine.¹ Coincidentally, issue 72 of NICE Eyes on Evidence has highlighted a systematic review that found that the majority of patients tended to overestimate the benefits, and underestimate the harm, of various healthcare interventions.2 Interestingly, it found that a correct estimation of benefit by at least 50% of participants only occurred for two outcomes, one of which was improved vision after cataract surgery.  

However, who would willingly go into the surgery if they truly believed that they would be one of those? How you explain risk has a big impact on peoples’ perception of it.

NICE recommends giving people information, and the support they need to make use of it, to promote their active participation in care and self-management. However, human nature being what it is, I suspect that - even if they are clearly told the risks and benefits - people still want to believe that the healthcare intervention being offered to them will be beneficial. Otherwise, they may think, why would it be offered? We all know that – for example – cataract surgery is a staggeringly successful operation, but complications do occur, and some people are worse off as a result. However, who would willingly go into the surgery if they truly believed that they would be one of those? How you explain risk has a big impact on peoples’ perception of it.

I don’t know how many of you do the lottery, but if you do you will probably be aware that the odds of winning a significant amount of money are pretty small (I have heard it said that the lottery is a tax on people who can’t do maths!). It is an interesting dichotomy that the same person may believe that they have a small chance of having a complication after surgery (let’s say that the complication rate is 5%), yet may still believe that they are in with a realistic chance of winning a life-changing amount of money on the lottery, even though the chances of that happening are considerably less than 5%. We could get into a discussion of the psychological reasons for this, but it is interesting to compare the two situations (which, I accept, are different partly because the lottery gives you a potential chance to win something, whereas the complications of cataract surgery are concerned with potentially losing something).3 The joys of explaining human nature! 

This applies to optometric practice too, as it is not uncommon to find that - even after you have carefully explained to the patient that there isn’t much of a change in their prescription - some patients optimistically still expect to be able to see better with new specs that you do for them regardless! I remember a long time ago I saw a lady for a routine sight test. I told her that there was no change in her prescription and she went away happy without having new specs. About a year later she felt her eyes had changed and so she decided to have some new specs done.  However, she didn’t mention that she felt her eyes had changed, or have another sight test, as she thought that simply having new specs done would improve things. Needless to say, they didn’t. 

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1 BMJ 2015;350:h2308

2 Hoffmann TC, Del Mar C.  Patients’ Expectations of the Benefits and Harms of Treatments, Screening, and Tests: A Systematic Review  JAMA Intern Med 2015;175(2):274-286  

3 See, for example, Kahneman D Thinking fast and slow

Dr Susan Blakeney FCOptom
Clinical Adviser, College of Optometrists

Susan graduated from City University. After a pre-registration year in multiple practice she was awarded the President’s Prize from the College. Since then, she has completed both bachelor and master of laws degrees and a PhD. She obtained a MA in Medical Ethics and Law from Kings College London and has completed the post graduate ophthalmic public health module at Leeds University. Susan was awarded Fellowship of the College in 2009.  She has completed the College’s Professional Certificate in Glaucoma and the Professional Certificate in Medical Retina. She currently practises part-time in independent practice, is a clinical adviser to the College of Optometrists, Optometric Adviser to NHS England, South (South East) and a Case Examiner for the General Optical Council.

 

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