‘Nudge letters’ reduced GP pathology requests by 42,000 a year: Lancet study
GPs who received ‘nudge letters’ from health officials cut back on frequently ordered pathology requests, according to new research on GPs who did not know they were test subjects.
The Federal Government-funded study found that GPs who received letters saying they were in the 90th percentile for ordering particular tests or test batteries reduced orders for those tests by 36% in the next six months.
The study looked at 10 common pathology batteries, all of which were some combination of iron studies, TSH, vitamin D, vitamin B12 and thyroid function.
GPs received four-page letters if they were both in the top 10% of requestors for such batteries and in the top 10% of requestors for at least two of the five individual tests in 2020/21.
Of 5964 GPs fitting these criteria, 625 were used as controls — avoiding one of the letters, signed by then-Chief Medical Officer Professor Paul Kelly.
“You may be aware that overuse of pathology testing has become a problem in Australia,” the letters read (see example below).
“Many requested tests have a low diagnostic value and do not result in a change to patient management.
“As part of the Department of Health’s commitment to the best practice use of pathology requesting,
I am writing to you because your requests for certain pathology test combinations are higher than
90% of GPs practicing [sic] in similar geographic regions in Australia.”
The RACGP, ACRRM and the AMA provided feedback on the letters’ style, said the researchers, led by Monash University in Melbourne.
The letters also included guidance from medical colleges on when the tests were clinically recommended.
GPs who received a letter cut back on the targeted tests by 36% in the next six months compared with the controls, with a slight rebound over the 6-12-month mark, they wrote in The Lancet Primary Care.
This translated to 24,062 fewer overall tests after six months and 41,925 fewer tests over 12 months, said the study authors, who included GP Professor Paul Glasziou.
For the tests highlighted in their letters, the GPs had averaged 26.9 requests per 1000 consultations, which dropped to 19.7 over the next 12 months.
“Our findings support the use of audit and feedback to reduce overuse of pathology test requests in general practice,” the researchers said.
While the letters provided an email and phone number for GPs to give feedback, the study said only seven GPs gave feedback that was disapproving or negative.
The researchers acknowledged that the study did not assess whether the tests GPs cut back on were clinically justified or not, merely pointing out the letters were sent “to the highest GP requestors of pathology test combinations that are commonly overused and unlikely to support diagnosis or patient health outcomes”.
“Careful review of the feedback and accompanying best practice guidance is likely to benefit, rather than harm, patients,” they added.
They said the GPs did not need to consent to be included because they would experience “no more than minimal risk of discomfort or inconvenience”.
Obtaining consent “would create a burden greater than the intervention itself”, they added.
The researchers also tested eight versions of the letter, such as a pamphlet format or letters that invited GPs to CPD-accredited education, but these did not significantly change the results.
They said the effect was among the largest seen in any randomised controlled trial of this kind, despite UK and Dutch trials showing no impact from similar interventions.
It is not the first time the government has used GPs as unknowing guinea pigs for research on nudge letters.
A 2022 JAMA study looked at 3000 GPs in the top 20% of referrers for certain imaging tests, including those for the cervical spine, shoulder, hip and knee.
Read more: Professor Paul Glasziou defends GP nudge letter experiment
More information: Lancet Prim Care 2026; 27 Apr.
