Using routine data to complement and enhance the results of randomised controlled trials.

BACKGROUND: Randomised controlled trials (RCTs) are widely accepted as the best way to assess the outcomes and safety of medical interventions, but are sometimes not ethical, not feasible, or limited in the generalisability of their results. In such circumstances, routinely available data could help in several ways. Routine data could be used, for example, to conduct 'pseudo-trials', to estimate likely outcomes and required sample size to help design and conduct trials, or to examine whether the expected outcomes observed in an RCT will be realised in the general population. OBJECTIVES: The project was undertaken to explore how routinely assembled hospital data might complement or supplement RCTs to evaluate medical interventions: in contexts where RCTs are not feasible for defining the context and design of an RCT for assessing whether the benefits indicated by RCTs are achieved in wider clinical practice. METHODS: The project was based on the system of linked Scottish morbidity records, which cover 100% of acute hospital care episodes and statutory death records from 1981 to 1995. Three case studies were undertaken as a way of investigating the utility of these records in different applications. First, an attempt was made to analyse the link between the timing of surgery for subarachnoid haemorrhage (SAH) and subsequent outcomes (a question not easily susceptible to RCT design). A subsample was derived by excluding patients for which a diagnosis of SAH may not have been established or that may not have been admitted to a neurosurgical unit, and the data were assessed to attempt to inform the design of a trial of early versus late surgery. Transurethral prostatectomy (TURP), the second case study, has become the surgery of choice for benign prostatic hyperplasia without systematic assessment of its effectiveness and safety, and an RCT would now be considered unethical. However, there is a need to investigate long-term effects and the influence of co-morbidities on outcomes. A retrospective comparison of mortality and re-operation following either open prostatectomy (OPEN) or TURP was, therefore, undertaken. Patients for whom it was not possible to establish the initial procedure were excluded. The third case study compared coronary artery bypass grafting (CABG) with percutaneous transluminal angioplasty (PTCA) for coronary revascularisation. RCTs have been conducted in limited patient subgroups with short follow-up periods. A meta-analysis of RCTs could be augmented by routine data, which are available for large populations. This would allow assessment of subgroup effects, and outcomes over a long period. A subgroup of patients was therefore constructed for whom relevant routine data were available and who reflected the entry criteria for major RCTs, thus enabling a comparison between the results expected from this subgroup and those of the general population. RESULTS AND CONCLUSIONS: The uses of routine data in these contexts had strengths and weaknesses. The SAH study suggested a means of assessing outcomes and survival rates following haemorrhage, which could have value in informing the design of more precise trials and in evaluating changes in outcome following the introduction of new treatments such as embolisation. However, the potential of the data was not realised because their scope and content were insufficient. For example, lack of data on the time of onset of symptoms and patients' conditions at hospital admission made it difficult to establish the link between timing of surgery and the outcome, and there was insufficient information on patients' conditions at discharge to enable a comparison of outcomes. The prostatectomy study was able to address questions not answered by RCT literature because the large number of cases it included allowed exploration of subgroup effects. (ABSTRACT TRUNCATED)

Seasonal variation in mortality in Scotland.

BACKGROUND: Seasonal patterns in mortality have been recognized for many years. This study assesses seasonal variation in mortality in Scotland between 1981 and 1993 and considers its association with socioeconomic status and outdoor temperature. METHODS: Lagged Poisson regression analysis of numbers of deaths and average weekly temperature with adjustment for serial autocorrelation and influenza epidemics. RESULTS: There was significant seasonal variation in weekly death rates with a difference of about 30% between a summer trough and a winter peak. This variation was principally attributable to respiratory disease, cerebrovascular disease and coronary artery disease. Seasonal variation in mortality fell from around 38% in 1981-1983 to around 26% in 1991-1993. There was no clear evidence of a relationship between socioeconomic status and seasonal mortality, however the extent of the fall in seasonal variation was greater in deprived areas than in affluent areas. Overall, a 1 degree C decrease in mean temperature was associated with a 1% increase in deaths one week later. The lag in this relationship varied by cause of death and underlying temperature. CONCLUSIONS: Seasonal variations in mortality and the relationship between temperature and mortality are a significant public health problem in Scotland. It is likely that the strength of this relationship is a result of the population being unable to protect themselves adequately from the effects of temperature rather than the effects of temperature itself.

Comparing outcomes of percutaneous transluminal coronary angioplasty with coronary artery bypass grafting; can routine health service data complement and enhance randomized controlled trials?

AIM: To compare outcomes of percutaneous transluminal coronary angioplasty (PTCA) with coronary artery bypass graft surgery (CABG) for a population stemming from routinely collected data, in order to assess the merits of such data sources as a complement, and possible enhancement, to randomized controlled trial results. METHODS AND RESULTS: A population of Scottish patients were taken from a routine discharge summary and from this data source patients comparable to those from randomized controlled trial settings were identified. Between 1989 and 1995, 12 238 pseudo randomized controlled trial patients were identified from the routine data set, of which 3714 (30.3%) received PTCA and 8524 (69.7%) received CABG. The baseline characteristics of the pseudo randomized controlled trial and randomized controlled trial patients were similar. The evidence from both the randomized controlled trials and routine data indicate that for 1 year follow-up the risk of cardiac death and/or non-fatal myocardial infarction is not significantly different between the two treatment groups. CONCLUSION: The outcomes expected of PTCA and CABG following trial evidence have been realized in the routine data which are representative of a complete, non-selective population. Due to the size of the routine data set it would be possible to set up hypotheses for potential subgroup effects at the outset.

League tables and acute myocardial infarction.

BACKGROUND: Comparison of the outcomes of care provided by hospitals is a growing trend. Outcomes need to be distinguished into those attributable to the practice of hospitals and those that arise from differences in the characteristics of patients and the underlying morbidity of the populations for whom hospitals provide care. We explored these issues for deaths in hospital or within 30 days of discharge after acute myocardial infarction in Scotland, UK. METHODS: We used records from December, 1992, to November, 1993, for 14,359 episodes of acute myocardial infarction, the death records of those who died, and 9391 death records for individuals who died after acute myocardial infarction but who had not been in hospital in the 30 days before death. Hospital discharge records were taken from the Scottish Morbidity Records. The outcomes we investigated were all-cause mortality within 30 days of discharge from hospital, and death from acute myocardial infarction at any time during the study period. We estimated separately effects attributable to patients' characteristics, hospitals, and areas of residence with multilevel modelling. FINDINGS: We found significant differences between hospitals by age, sex, and medical history. The odds ratios for death ranged from 0.62 (95% CI 0.50-0.80) to 1.28 (1.07-1.59), relative to the average performance for Scotland as a whole. Analysis including area of residence, deaths occurring out of hospital, and more detailed information about patients showed no significant differences between hospitals for patients aged 70 years. By postcode area, there was a strong association between out-of-hospital deaths and deaths in hospital or shortly after discharge. INTERPRETATION: Hospital outcomes may vary from one subgroup of patients to another and should be assessed independently of patients' areas of residence. Measures of performance that do not provide valid comparisons could diminish public confidence in hospital services.

Deprivation and mortality in Scotland, 1981 and 1991.

OBJECTIVE: To compare the mortality experience of Scottish postcode sectors characterised by socioeconomic census variables (Carstairs scores) in 1980-2 and 1990-2. METHODS: Variables derived from the 1981 and 1991 censuses were combined according to the method devised by Carstairs and Morris to obtain Carstairs scores for 1010 postcode sectors in Scotland in 1981 and 1001 sectors in 1991. For most analyses, these scores were grouped into seven deprivation categories ranging from affluent (category 1) to deprived (category 7) localities. MAIN OUTCOME MEASURES: Death rates and standardised mortality ratios for localities according to deprivation category. RESULTS: Postcode sectors in Scotland that were categorised as deprived in 1981 were relatively more deprived at the time of the 1991 census; the mortality experience of deprived localities relative to either Scotland or affluent neighbourhoods worsened over this period, with a 162% difference between the most affluent and most deprived categories in 1991-2. Although the age and sex standardised mortality for ages 0-64 in Scotland declined by 22% during the 1980s, the reduction in the deprived categories was only about half that of the affluent groups. Increases in the death rate for men (29%) and women (11%) aged 20-29 in the deprived groups were largely attributable to an increase in the rates of suicide. Death rates from ischaemic heart disease and carcinoma of the lung and bronchus at ages 40-69 were lower in all deprivation categories in 1990-2, but the reduction was greater in more affluent areas; the difference in rates for these conditions between affluent and deprived groups therefore increased over the decade. The observed worsening of the standardised mortality ratio for Glasgow relative to Scotland could be explained on the basis of these mortality differentials and the concentration of deprived postcode sectors in Glasgow. CONCLUSIONS: Differences in mortality experience linked to relative poverty increased in the 10 years between 1981 and 1991 censuses. Although mortality for Scotland as a whole is improving, the picture is one of an increasing distinction between the experience of the majority and that of a substantial minority of the population.

Measures of performance in Scottish maternity hospitals.

OBJECTIVE: To develop measures of hospital performance over time with particular reference to maternal and neonatal care by controlling for case mix. DESIGN: Analysis of computerised records of births. SETTING: Scotland, 1980-7. SUBJECTS: Over half a million singleton live births and stillbirths. MAIN OUTCOME MEASURES: Numbers of perinatal deaths and caesarean sections. RESULTS: Scottish maternity hospitals perform more or less equally with regard to perinatal mortality. When caesarean sections are considered, there is evidence that hospitals differ in their treatment of different groups of women; in two examples one hospital had an increased rate among women of parity 2 or more and another had a reduced rate of repeat caesarean section. CONCLUSIONS: Developing measures of performance over time by controlling for case mix is a valid system for monitoring hospital outcomes and activity, and allows comparison either between hospitals or with data for all Scottish maternity hospitals. Hospital profiles permit identification of differences for particular patient groups after allowance is made for other case mix variables.

General practitioners and opiate-abusing patients.

General practitioners' involvement with patients who abuse opiates has increased in recent years but little is known about the difficulties they may encounter in working with such patients. This study examined a series of general practitioner consultations with patients who were abusing heroin and describes the problems that arose. Manipulative behaviour, lying about symptoms and a lack of motivation to give up drug use were common among drug abusers; by such behaviour, the patients failed to satisfy the underlying assumptions on which the doctor-patient relationship ordinarily depends. There is a need to evolve alternative approaches for the care of this group of patients which will help general practitioners to establish more effective relationships with them.

Preventive dentistry in a health centre: effectiveness and cost.

The clinical and economic effects of a programme of preventive dentistry for children in an inner-city health centre are compared with those for traditional restorative care. Reductions in the rate of dental caries are estimated to be 70% for children aged 4-6 after 4 years in the programme (dmft) and 85% for children aged between 7 and 10 years after 4 years (DMFT). The cost-effectiveness analysis on which the economic appraisal is based identifies the issue of differences in the quality of output as critical to choices between the two treatment regimes. The preventive programme was primarily intended for pre-school children; for this younger group, assumptions about the quality of the preventive outcome would have to value it at between 0.8 and 1.2 times the quality of the restorative outcome in order to make up the difference in cost between the two regimes. For 7-10 year olds, the 4-year analysis showed the preventive programme to be more costly than restorative care largely because of low rates of incremental change at these ages. These rates were partly influenced by the design of the study and partly by the eruption status of the permanent dentition across this age-group. There is a need for further study of measures of dental outcome which combine aspects of both the quality and length of life of teeth.

Perinatal mortality in Scotland: 1970-9.

An examination of the recent decline in perinatal mortality in Scotland during the 1970s showed that despite substantial changes in fertility and the demographic pattern of births, differences in the age, parity, and social class composition of the obstetric population in this decade accounted for just 7% of the overall improvement in perinatal mortality between 1970 and 1979. The general pattern of relative risks associated with maternal age, parity, and social class remained largely unchanged. Marginal changes in the birthweight distribution, however, were sufficient to account for 13% of the reduction in perinatal mortality. The low birthweight infant, especially those weighing under 1500 g, assumed increasing importance as a factor in perinatal mortality owing to a progressive worsening in the relative risk of perinatal mortality associated with low birth weight. Although regional differences in perinatal mortality persisted over this period, there occurred some lessening of the traditional inequality between western and eastern parts of the country. Finally, registered causes of perinatal mortality are reviewed. In the absence of other explanations the results of this analysis, collectively, suggest that much of the recent decline in perinatal mortality was perhaps due to changes in obstetric practice and in the clinical management of neonatal morbidity.

Patients in acute surgical wards: a survey in Glasgow.

A survey was made of all patients in general surgical, urological, and orthopaedic and accident wards in Glasgow on one day in June 1975. Its purpose was to define features of acute surgical practice of relevance to the future planning of resources, particularly bed numbers. Over 40% of the patients in both surgical and orthopaedic wards were over 65 years. Most patients had serious conditions and could not have been treated other than by admission to an acute surgical ward. But a substantial minority no longer needed such facilities and could have been transferred to second-line beds, although many still required skilled nursing care. Delay in the discharge of elderly patients from acute surgical wards as a consequence of non-surgical (often medical or social) problems results in a proportion of acute surgical beds fulfilling a second-line function. Unless arrangements for the earlier discharge of these patients are made any reduction in acute surgical beds is likely to restrict elective surgery, especially in orthopaedics.