An investigation into five GPs whose patients showed a high mortality has found no evidence of negligence or malpractice.

The review was carried out after the Shipman inquiry was notified of 12 GPs whose patients had an excessively high mortality. The inquiry recommended that the practices be investigated. An inquiry into two of them in the West Midlands, completed last year, had also found no evidence of wrongdoing (BMJ 2004;328: 1474).

The latest investigation found that the large number of nursing home patients on the GPs' lists was likely to have been responsible for the high mortality.

An article published online ahead of print on 6 July in the Journal of Public Health (http://jpubhealth.oxfordjournals.org, doi:10.1093/pubmed/fdi043) warns that such inquiries are costly and time consuming.

“The introduction of a national mortality monitoring system for GPs requires careful consideration of the consequences, not only for individual practitioners flagged up as having excessive mortality rates, but also for the primary care organisations that may be expected to conduct follow-up investigations, but in many cases will lack the resources as well as the expertise to carry these out,” wrote the authors, from Imperial College, London, the National Clinical Assessment Authority, and the Adur, Arun and Worthing Primary Care Trust.

“The review enabled us to assess the quality of care provided by these five GPs, and increased our confidence in the final conclusion that there was no evidence of malpractice or negligence. Yet our investigation was resource-intensive, with direct and opportunity costs that ran into several thousands of pounds,” they wrote.

The report says that in December 2004 the Shipman inquiry recommended the development of a national system for routinely monitoring death rates among patients of general practices. “Yet it remains unclear who should be responsible for investigating GPs flagged up as having unusually high death rates by such a system, or what methods should be used,” it says.

The review involved a retrospective analysis of routine mortality data and patient registration data from five general practices in West Sussex and a review of the case notes of deceased patients. Outcome measures included standardised mortality ratios, the proportion of deaths in nursing homes, and reviewers' concordance with GPs' decisions on issue a death certificate.

Standardised mortality ratios for the practices ranged from 145 to 239 (against a standard set for West Sussex of 100), and all differences from the West Sussex average were statistically significant (P<0.02).

There was no association between the high death rates and the age and sex composition of each GP's patient population. But the death rates did correlate highly with the proportion of deaths occurring in nursing homes. The results show that more than a third of the deaths occurred in nursing homes (nationally about 11% of deaths occur in nursing homes).