Half of all formal patient complaints made in Australia to health ombudsmen concern just 3% of the country's doctors, with 1% accounting for a quarter of all complaints, finds research published online in BMJ Quality & Safety.
Doctors complained about more than three times are highly likely to be the subject of a further complaint - and often within a couple of years - the findings show.
The problem is unlikely to be confined to Australia, warn commentators, who point out that while regulators often know about these problem doctors, patients usually don't.
The researchers base their findings on a national sample of almost 19,000 formal patient complaints filed against 11,148 doctors with health service ombudsmen (commissions) across Australia between 2000 and 2011.
Over 60% (61%) of the complaints concerned clinical aspects of care, while almost one in four (23%) concerned communication issues, including the doctor's attitude and the quality or quantity of information provided.
Most (79%) of the doctors involved in complaints were men, and over half of all those complained about (54%) were aged between 36 and 55.
When the distribution of complaints was analysed across all doctors in practice, this showed that 3% of practitioners accounted for 49% of all complaints made; and 1% accounted for a quarter.
The researchers looked at factors that might help to flag up those doctors at high risk of attracting further complaints.
Male gender, older age, and working in surgical specialties were all associated with a higher risk of repeat complaints. But the number of previous complaints was the strongest predictor.
Doctors named in a third complaint had a 38% chance of being named in another one within one year, while those with 10 complaints against them were virtually certain to add another to their total within 12 months.
The authors argue that the approach they used to predict complaint risk could be used to spot problem doctors earlier, so improving the quality and safety of patient care.
In an accompanying editorial, Professor Ron Paterson, of the Faculty of Law at the University of Auckland in New Zealand, comments that few people will be surprised that a group of "frequent flier" doctors attract a disproportionate share of complaints.
"What is surprising is the extent of the problem," he writes, describing it as "an albatross around the neck of the Australian medico-legal system - and a problem likely to be replicated in other countries, even though the regulatory actors may differ."
He advocates that three or more complaints about a doctor should become a matter of public record. "The current veil of secrecy over most complaints (which avoid publicity by never reaching the stage of disciplinary proceedings) allows repeat offenders to continue unheeded," he suggests.
Countries should follow the example of the UK doctors' regulator, the General Medical Council, and introduce formal appraisal of a doctor's practice as part of revalidation, he argues.
In another editorial, Drs Thomas Gallagher and Wendy Levinson of the Universities of Washington and Toronto, respectively, reiterate that the findings are unlikely to be unique to Australia, and warn that the true extent of the issue is likely to be much greater than formal complaints would suggest.
They caution against dismissing communication problems as irrelevant: doctors who find it difficult to talk to patients often find it hard to communicate with colleagues, they say, while the evidence suggests that poor communication has an impact on safe and high quality care, they add.
"The critical first step is for all of us to begin speaking up when we know that a colleague is struggling in their interactions with patients and with peers," they write.
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Identification of doctors at risk of recurrent complaints: a national study of healthcare complaints in Australia, Online First, doi 10.1136/bmjqs-2012-001691
Not so random: patient complaints and 'frequent flier doctors, Online First, doi 10.1136/bmjqs-2013-001902
Physicians with multiple patient complaints: ending our silence, Online First, doi 10.1136/bmjqs-2013-001880