There is a considerable furore surrounding the new proposal to pay GPs £55 for each dementia diagnosis. The Patients Association called it “a step too far” that would mean a “bounty on the head” of some patients (link), while the Daily Mail quoted a GP as describing the programme as ‘an intellectual and ethical travesty.’ Vitriol aside, there are clearly some issues with incentivising clinicians on the basis of making diagnoses.

Payment by diagnosis could be compared to other schemes, such as the Pay for Performance (P4P) scheme, which Sutton et al (2012) demonstrated had a mortality reducing effect in hospitals in England. However, P4P created incentives by paying doctors on the basis of specific process variables, such as prescribing aspirin at discharge for patients with acute myocardial infarction. These incentives act by altering the opportunity cost of time. For clinicians qua clinicians they may prioritise their time differently in order to increase their revenue from medical practice so that they are more likely to engage in clinical tasks with higher earnings potential. For clinicians qua individuals they may allocate more time to labour, substituting from leisure or work at home, at the benefit of patients. The P4P interventions operate at a specific part of the healthcare causal chain, at the level of process or specific interventions, which may then generate an increase in detection rates or a reduction in adverse events, all leading to improved patient outcomes. Incentivising physicians by diagnosis, however, operates at a different part of the healthcare process. Certainly, the payment for diagnosis may ensure GPs spend more time diagnosing or working with potential dementia patients, in order to boost dementia detection rates; however, equally, a diagnosis per se does not require much time to make and doctors may be incentivised to make incorrect diagnoses. Furthermore, in distorting the opportunity costs of physician time, GPs will allocate more time to identifying dementia patients at the potential risk of neglecting other patients.

Dementia is a concern for an ageing population. Only around 50% of dementia cases are thought to have been diagnosed. The global burden of dementia and Alzheimer’s disease was estimated to be $422 billion in 2009, of which $124 billion was unpaid care (Wimo et al, 2010). One strategy for reducing the burden of dementia is earlier detection – before the development of frank dementia most patients have a period of cognitive decline and suffer from what is termed mild cognitive impairment (MCI) (Petersen et al, 1999). While the deterioration of cognitive function is inexorable in dementia patients, it may possibly be slowed with appropriate therapy, which would then potentially delay or prevent a patient requiring highly costly care for late stage dementia (Gestios et al, 2010, 2012, Petersen et al, 2005, Teixera et al, 2012). There would also be considerable benefit to people with MCI and their families where the devastating impact of dementia can be reduced. Whether or not an incentive for dementia diagnoses would lead to earlier detection remains to be seen. Nonetheless, it would seem that incentivising testing for MCI in order to improve early detection, would be a more appropriate strategy. Indeed, this is the aim with type 2 diabetes where the potential benefits of a screening programme have been discussed widely (Gillies et al, 2008, Kahn et al, 2010, Schaufler and Wolff, 2010, among many examples). Simply paying doctors every time they diagnose a case of diabetes would, at face value, be less effective, particularly since earlier cases may be harder to detect – the harder to detect cases would require more time on the part of the clinician, the marginal benefit of which may be smaller than the marginal cost to the clinician. Incentivising for conducting tests arguably does not discriminate on the same basis.

While this may be a step in the right direction to improve dementia detection rates, there may have been a more effective method of incentivising GPs than payment by diagnosis.

By Sam Watson Health economics, statistics, and health services research at the University of Warwick. Also like rock climbing and making noise on the guitar.

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