Results

The median age of the study group was 57 years (range 22–80) 78% of the group were female. Table 1 shows the clinical characteristics of the RA patients at study entry. Overall 95 patients (47.5%) of the study group had died by 12 years of follow up. Table 2 shows the summary causes of death. Most RA patients died of cardiorespiratory causes and malignancy. There was one drug related death (methotrexate) in this cohort in a 66 year old female who despite close monitoring developed sudden pancytopenia after 18 months of methotrexate (low dose 7.5 mg/weekly). She died in the intensive care unit of pulmonary haemorrhage and infection.

There were more patients in the most deprived Carstairs categories in this RA cohort (6 and 7=26%) than in the general population in Scotland (6 and 7=18%) or in England and Wales (6 and 7 =5%). There were also fewer patients living in affluent areas (Carstairs 1 and 2 = 12%) compared with 18% for West of Scotland, 20% for Scotland overall and 52% for England and Wales. Table 3 shows that the age and disease duration distribution in the various Carstairs groupings at study entry were similar, as would be expected given universal access to health care in the United Kingdom. Table 4 displays the age at death and distribution of deaths by initial Carstairs score: it can be seen that the median age at death was lower and the percentage of deaths was higher in Carstairs 6 and 7. Figure 1 shows survival by deprivation category, which illustrates that category 1 and 2 (the most affluent) have better survival than those in the other Carstairs areas. Table 5shows the relative rates of all cause mortality by deprivation category adjusted for age and sex (patients in Carstairs groups 6 and 7 (the most deprived) have 1.66 times the mortality experience of Carstairs groups 1 and 2). Median age at death for men was 63 years (range 48–76) and for women 69 years (range 53–85). Data on smoking patterns (not shown) demonstrated that smoking is more prevalent among people from the more deprived areas.

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Figure 1

Twelve year survival curves by deprivation category.

There was a variation in HAQ score (function) by Carstairs groupings at the outset: those in the most affluent areas 1 and 2 had a HAQ score of 2.25, the same as those in 3, 4 and 5, while those in the most deprived areas 6 and 7 had a HAQ score of 2.5. Kruskal-Wallis indicated a significant difference between 6 and 7 and the other groupings (p=0.04).

Some 47.5% of the RA patients in the study had died by 12 years. Sixty one per cent of the most deprived patients (Carstairs 6 and 7) had died compared with only 36% in Carstairs 1 and 2. Overall in “intention to treat” groups, 50 of 98 penicillamine (51%) and 45 of 102 (44%) of the sulfasalazine group were dead by 12 years. Table 6 shows the mortality rate per person years of follow up by deprivation category.

Cox proportional hazards regression identified age and HAQ functional score as significant predictors of mortality for the RA patients. However, entering both age and HAQ together into the model caused HAQ to lose its significance.

Discussion

This study shows that in patients with RA increasing deprivation is associated with higher mortality. Study patients were assigned to deprivation categories based on an ecological index relating to the postcode area of residence. This may have led to misclassification of economically deprived patients living in affluent areas and so to an underestimation of the association between deprivation and mortality (although it is also possible for misclassification to have had the opposite effect). This RA cohort included many patients with severe disease as indicated by the high median HAQ score at outset and the demonstration of high mortality cannot necessarily be extrapolated to patients with milder disease. Nevertheless, RA of this severity is associated with considerable morbidity and mortality, as might be expected. Patients who are socially disadvantaged in the West of Scotland are more likely to have poorer functional scores33 and are also more likely to die prematurely. Others have shown that the discrepancy in HAQ scores are present at the outset of RA and are therefore unlikely to reflect the disadvantage that comes with a chronic disease.34 While it is possible that this aspect is contributory it is clear that RA is associated with more functional impairment and greater mortality among the patients in the most disadvantaged areas. Progressive disability may worsen cardiovascular risk factors such as lack of exercise, poor diet, obesity and smoking. There has been some speculation that RA is becoming less severe35 but change in disease characteristics may reflect improved resources leading to fewer patients with severe disease attending any one centre rather than a true improvement in the disease.36 It is also possible that some lifestyle changes have had a beneficial effect but these remain complex and difficult to unravel.

Leigh and Fries have suggested that corticosteroid use is associated with an increased likelihood of dying prematurely,37 5 of 15 (33%) of those who died from sepsis, renal disease or gastrointestinal disease had been taking systemic corticosteroids while overall corticosteroid use in our cohort was low (8%) among survivors at 12 years.

A cross sectional analysis of mortality by country of birth has shown that mortality from all causes is higher in Scottish immigrants38 and smoking has recently been shown as a risk for development of RA in men.39 In this study fewer RA patients were affluent (Carstairs 1 and 2) relative to the population of the West of Scotland. The proportion of affluent patients is much smaller in Scotland compared with England and Wales.

The significant predictors of mortality in RA found in this investigation were consistent with other studies.4 ,7 A new finding, however, is the association between mortality and Carstairs score indicating that deprivation in patients with RA is associated with increased mortality rates. It remains to be shown how universal these findings are. It seems probable that there will be parallels in most Western countries. Any planned prospective study would need to be conducted in an area where there is a full spectrum of social advantage and disadvantage. This observation is particularly relevant in the context of increasing relative deprivation in Great Britain and is especially ironic given the universal free access to education and health services over the past 50 years.

What is it that leads to the association between deprivation and health in RA? The broader issue has been explored eloquently by Sir Douglas Black in his paper on deprivation and health.40Explanation of the association between deprivation and mortality in the general population is thought to lie in variation in health related behaviour and lifestyle (smoking, diet, alcohol intake, efficiency in using disease prevention strategies) as well as social structure and material living conditions (education, income, housing, pollution).41 The adverse effect of deprivation on mortality may be exacerbated in patients with chronic diseases relative to the general population. A chronic illness such as RA that leads to progressive disability and reduced mobility may worsen the burden of psychosocial stress and increase the frequency of cardiovascular risk factors such as obesity, lack of exercise, poor diet and smoking all of which are already more prevalent among the deprived. It seems probable, although studies are awaited, that deprivation will lead to premature mortality among patients with most chronic, disabling diseases.

These findings have implications for rheumatologists and other chronic disease specialists, who because of the long term nature of their patient-physician relationships, are in a position to give sustained advice on health related behaviour as well as in identifying and treating medical risk factors such as hypertension, smoking, obesity and hyperlipidaemia, osteoporosis, gastrointestinal disease and dietary deficiencies. Graded exercise programmes may be difficult to achieve in patients with RA but a multidisciplinary approach should be attempted. Tackling these aspects along with a concentrated effort to change diet and social habits might have a bigger impact on the outcome of RA than combination DMARD treatments or minor refinements in available treatments—an area considered by Callaghan and Pincus.42Whether this goal is achievable remains to be shown, but the complexity of managing RA will certainly escalate as these issues are investigated.

In conclusion, these findings, if confirmed elsewhere, have implications for the interpretation of cooperative studies that bridge areas of affluence and deprivation—the outcome might well be very different in discrepant areas and assumptions about severity of disease and functional impairment will require close scrutiny. Finally, there are considerable implications for resource allocation for RA patients, and training programmes for rheumatologists.