The risk of litigation has not been given a great deal of attention in primary care, say the authors. But with most healthcare contacts taking place in primary care, it is important to characterise the causes and types of claims arising from these encounters, they add.

They carried out an extensive trawl of published research in English about the number and causes of malpractice claims in primary care in April 2012 and again in January 2013.

Out of a total of 7152 studies, 34 were eligible for inclusion in the analysis. Fifteen studies were based in the US, nine in the UK, seven in Australia, two in France, and one in Canada.

In the US, studies indicate that malpractice claims brought against primary care doctors accounted for between 7.6% and 16% of the total. In the UK, GPs made up the greatest proportion of an overall 20% increase in claims between 2009 and 2010, with claims against them more than doubling between 1994 and 1999.

And in Australia, GPs accounted for the highest proportion of claims and the highest number of new claims on the national Medical Indemnity National Collection database for both 2009 and 2010.

Missed diagnoses were the most common source of malpractice claims, accounting for between a quarter (26%) and almost two thirds (63%) of the total. And the most common consequence of this in the claims filed was death, ranging from 15% to 48% of claims made for missed diagnoses.

Among adults, cancer and heart attack were the most commonly missed diagnoses in the claims made. Others that cropped up frequently included appendicitis, ectopic pregnancy, and fractures. Among children, the most frequent claims related to meningitis and cancers.

The second most common sources of malpractice claims were drug errors, the proportion of which ranged from 5.6% to 20% across all the studies.

A substantial proportion of claims were unsuccessful, with only one third of US claims and half of UK claims ending up in a pay-out. But while the number of claims brought against US doctors has remained fairly stable over the past two decades, those brought against Australian and UK GPs have been rising.

The authors acknowledge that it may be difficult to generalise their findings as the term 'primary care' does not mean the same thing in all the countries studied, and none of the healthcare systems is the same. Using legal claims as a proxy for adverse events also has its limitations, they add.

But they point out that the threat of litigation can result in "defensive medicine" and over diagnosis and treatment, and that doctors who find themselves on the end of a malpractice claim, often find the process very distressing.