The recent publication by the NHS Centre for Reviews and Dissemination of the second edition of the guidance on undertaking systematic reviews of research on effectiveness gives increased recognition given to the diverse types of evidence that can contribute to systematic reviews.

Qualitative research is given explicit consideration in the new guidance. This is consistent with other recent recommendations emphasising the contribution of qualitative evidence to healthcare evaluation. There remain several issues, however, that need to be addressed in making the role of qualitative evidence in reviews more systematic.

Qualitative research has contributed to a number of published reviews, though rarely of the Cochrane type and often in relatively informal ways. Several issues still need to be dealt with to make the role of qualitative evidence in reviews more systematic.

Firstly, the centre’s guidance rightly emphasises the need for rigour in the identification of research. Searching for and identifying appropriate qualitative research remains frustrating and difficult. This is partly because there is no equivalent of the Cochrane controlled trials register or other clinical trials registers for qualitative research and partly because indexes and search filters require substantial improvement.

Secondly, the problem of how to appraise the quality of qualitative studies remains. Constructing hierarchies of evidence for types of qualitative research studies is problematic. More generally, there has been a failure to agree on suitable methods for assessing the quality of qualitative research. This has inhibited the development of a process similar to CONSORT, which aims to improve the reporting of clinical trials.

Thirdly, a formidable question is how to make qualitative evidence – which may be produced with widely varying theoretical perspectives and diverse analytical approaches – submit to the disciplines of secondary summary and synthesis.

A daunting array of theoretical and practical problems awaits reviewers who attempt the secondary manipulation of the concepts or themes that are the staple product of qualitative research. A natural tension exists between an approach that relies on interpretation and reflection (qualitative research) and an approach that seeks to expunge the potential for anarchy associated with such ungovernable processes (the systematic review).

Ref to NHS Centre for Reviews & Dissemination

After the introduction of conjugate H influenzae b vaccines the United States has seen a 73% reduction in the incidence of paediatric bacterial meningitis, with fewer than 3000 cases each year. A meta-analysis of 1602 prospectively enrolled children with bacterial meningitis from 19 studies in Europe and North America found that 4.5% died, but at least one major adverse outcome was present (severe intellectual disability, spasticity, paresis, seizures, deafness) in 16.4% of survivors.

There are few reports of the long term complications of bacterial meningitis. A Canadian study of 97 survivors of H incluenzae b meningitis identified by chart review found that those suffering acute neurological complications (seizures, coma, focal neurological deficits, hearing loss) had poorer school performance and more behaviour difficulties than their siblings.

These findings were extended by a prospective cohort study from Melbourne, where 130 school aged children were assessed seven and 12 years after meningitis. Though they achieved average scores on measures of intelligence, learning, and high level neuropsychological skills, after adjusting for socio-demographic variables these scores were consistently below those of age and grade matched controls. Only 53% of children experiencing acute neurological complications were judged as normal, while those presenting during infancy performed especially poorly on language and reading measures and complex learning tasks. There were also increased behaviour problems over time, possibly from academic difficulties and low self-esteem.

Twelve years after meningitis, 38% of patients had either major neurological, auditory, or intellectual impairments or functionally important behaviour or learning disorders impeding their academic performance. In comparison, 11% of controls had minor functional disabilities. Similar findings of cognitive and behaviour impairment have recently been observed in another prospective cohort study in which 115 survivors of meningococcal disease from Liverpool were compared 10 years after their illness with age and sex matched controls.

A questionnaire survey of parents and general practitioners about 1717 children aged 5 years who had had meningitis during infancy, was undertaken together with matched controls. The children were originally identified by a prospective national study of infantile meningitis in England and Wales in 1985-7.

Those who had had meningitis were at significantly greater risk of disability across all health, developmental and behavioural categories tested, but especially in the domains of learning and neuro-motor function. At greatest risk were neonates and those infected by S pneumoniae and their original illness had died by the age of 5 and at least half of these deaths seemed attributable to complications of meningitis.

The strengths of this study include its prospective design, recruitment restricted to infants within a national population base, large numbers affected by different pathogens, and high retention rates. This provides future opportunities for comprehensive neuro-psychometric assessments during school years and into adolescent and adulthood.