Socioeconomic and gender inequities in access to coronary artery bypass grafting in Finland

Transcription

1 EUROPEAN JOURNAL OF PUBLIC HEALTH 1997; 7: Socioeconomic and gender inequities in access to coronary artery bypass grafting in Finland ILMO KESKIMAKI, SEPPO KOSKINEN, MARJO SALINTO, SEPPO ARO * This study describes socioeconomic and gender differences in the use of coronary artery bypass grafting in relation to the need and regional supply of these operations in Finland. We established the rates of bypass operations performed for patients aged years by social class, education and disposable income and compared the operation rates to mortality from and risk of hospitalization due to coronary heart disease in the same socioeconomic groups. The data on bypass operations and hospital use were derived from a data set linking individually the 1988 Finnish Hospital Discharge Register and the 1987 population census. The data on coronary heart disease mortality came from a similar linkage scheme of the cause of death registers and the 1985 census. Among men, coronary bypass was more common for those in high socioeconomic categories for the variables analysed and in all age groups. These disparities in operation rates were inverse to the socioeconomic gradients in mortality from and risk of hospitalization due to coronary heart disease. Among women, the socioeconomic trends in surgery rates were not similar for all socioeconomic variables, but in relation to need showed higher use among the better-off. In relation to hospitalization due to coronary heart disease, women received proportionally less surgery than men. In hospital districts with the lowest overall bypass surgery rates, the distribution of operations more clearly favoured men and high socioeconomic groups than elsewhere. In the late 1980s clear discrepancies existed between the need for and use of coronary artery bypass surgery across socioeconomic groups in Finland. Some evidence also suggested corresponding inequities between genders. Key words: equity in health care, coronary artery bypass grafting, coronary heart disease, socioeconomic factors, Finland equity has been a major objective in Finnish health policy since the 1960s. One consequence of this has been efforts to ensure equitable access to appropriate health services across the entire population. In practice, regional equity in the allocation of health care resources has been emphasized, while issues such as socioeconomic or gender equity have received less attention. Universal access to care and nominal or non-existent fees for most services have long been assumed to guarantee equity in the availability of health care. Recent studies on the socioeconomic distribution of overall ambulatory and hospital services reveal that the Finnish health care system is fairly equitable from this perspective. 1 ' 2 However, there is little evidence concerning socioeconomic equity in access to individual treatments. In Finland, coronary artery bypass grafting has been the subject of intense public discussion, with the main focus being scarcity and regional disparities in the supply of the procedure. Socioeconomic or gender inequities in access have neither been debated nor studied. * I. Keskimaki 1, Seppo Koskinen 2, Marjo Salinto 1, Seppo Aro 1 1 Health Services Research Unit. Stakes, National Research and Development Centre for Welfare and Health, Helsinki, Finland 2 Population Research Unit Department of Sociology, University of Helsinki, Helsinki, Finland Correspondence: llmo Keskimaki, senior researcher, MD, Stakes, National Research and Development Centre for Welfare and Health, Health Services Research Unit P.O. Box 220, FIN-005 Helsinki, Finland, tel , fax In this study we assessed socioeconomic and gender differences in the utilization of coronary artery bypass grafting in Finland. In order to evaluate the extent to which the deployment of bypass operations corresponds to the need we compared their use in socioeconomic and gender groups to 2 population level morbidity indicators: mortality from and risk of hospitalization due to coronary heart disease. In addition, we analysed the effect of regional supply on the socioeconomic and gender differences in the utilization of bypass operations. DATA AND METHODS Data sources We established the rates of bypass grafting and hospital utilization for coronary heart disease for all patients aged years from the 1988 Finnish Hospital Discharge Register. The register covers all public and private hospitals in Finland and records the patient's residence, personal identification number and clinical data, e.g. 3 diagnoses, operation room procedures with 2 procedure codes and the patient's discharge status. The accuracy of these data is generally good 3 and approximately 95% of hospital discharges and 90-95% of surgical procedures are recorded in the register.^ The 5 public and 2 private Finnish hospitals which offer this procedure reported performing a total of 1,979 coronary artery bypass operations in The 1988 hospital discharge register has 1,879 operations filed. One of

2 Inequities in coronary bypass surgery the private hospitals, which began these operations only towards the end of the year, registered only non-specific data on operation room procedures but no specific procedure codes. For this hospital we formed the procedure data by selecting the discharges of patients aged 40 years or more with an operation room procedure, a principal discharge diagnosis of ischaemic heart disease (ICD-9: ) and an admission date after the hospital started operations. We thereby obtained 66 of the 88 bypass operations (75%) performed in the hospital. For the other hospitals the numbers of procedures in the register exceeded 95% of the 1988 hospital reports. 6 Procedures in the discharge register were recorded according to the classification of procedures issued by the Finnish Hospital League. 7 Because the classification does not include a code for coronary angioplasty, we were not able to analyse the rates for approximately 300 angioplasties performed in Finland in To obtain the socioeconomic data, hospital discharges were linked to the 1987 population census. Occupations were obtained from the 1970, 1975, 1980 and 1985 censuses in order to determine prior occupational status for the retired persons as well. Census data were found on 95% of the patients. Mortality from coronary heart disease in socioeconomic groups was calculatedfroma data set linking the cause of death registers, the 1985 population census and occupational datafrom the 1970,1975 and 1980 censuses. The linkage procedure, calculation of person-years and mortality figures have been described in detail elsewhere.^ Socioeconomic variables Occupation and education in the hospital and mortality data were based on the same primary data sources and classified identically. Social class was defined according to the person's occupation as follows. Upper white-collar employees: upper-level administrative, managerial or professional employees. Lower white-collar employees: lower-level administrative or clerical employees. Blue-collar workers: skilled or unskilled manual workers. Farmers: fanner employers or farmers on own account. Others: employers, self-employed workers, students or occupation unknown. Married women were allocated their own occupation or, if not employed, their husband's. The occupational status of retired persons was derived from their most recent occupation in the censuses of 1970, 1975, 1980 or The level of education was classified into 3 categories. High: usually a university degree or an examination requiring 13 years or more of education. Intermediate: secondary school and vocational training or high school matriculation requiring years of education. Low: basic education of less than 10 years. Disposable income was derived from the 1987 registers on taxes and welfare benefits. It was adjusted for family size using the OECD equivalence scale, where the first adult of a family is weighted as 1.0, other adults as 0.7 and children less than 18 years old as O.5. 9 Disposable income was not available for the mortality data set. Statistical methods The need for bypass operations was assessed using 2 proxies for need. We compared the age- and gender-specific mortality and annual risk of hospitalization for coronary heart disease in occupational and education groups against the respective rates of bypass operations. Five year age categories were used in plotting the death rates and risks of hospitalization against the operation rates. From the same data we calculated inequity indices derived from Kakwani's index of tax progressivity. This index compares the concentration curves for need and utilization parameters across socioeconomic strata. The details of the index calculation are from Wagstaff et al., 11 who proposed it for assessing horizontal equity in health services utilization. Because the index assumes an ordinal classification of socioeconomic variables, the occupational categories for 'farmers' and 'others' were excluded. To study the effect of regional supply of bypass operations on gender differences and socioeconomic gradients in operation rates, we categorized the hospital districts according to their age- and sex-standardized operation rates into 4 groups of similar population size. For each group we then determined gender-specific bypass operation rates by socioeconomic status. For gender comparisons in these and the national level analyses, men's and women's utilization and death rates were standardized for age against the total population. RESULTS According to the 1988 Finnish Hospital Discharge Register, coronary artery bypass operations performed on patients aged years numbered 1,416 for men and 9 for women, corresponding to 181 and 36 per 100,000 at risk respectively. Surgery rate gradients among men favoured those of high status according to all socioeconomic variables. The gradient was steepest for disposable income (table I). For women, the rate of surgery was 20% of the men's, for coronary heart disease mortality 24% and for hospital use approximately 40%. Among women, no clear gradients existed in surgery rates for social class and income groups. For education, the gradient favoured those with low education. However, there were only 10 operations among women with high education, which decreased the statistical significance of the inverse trend. Gender differences in surgery rates tended to be smaller in lower socioeconomic groups, but this was also the case for mortality and hospital use. Socioeconomic trends in hospital utilization and coronary heart disease mortality contrasted with the gradients in surgery rates. The lower the socioeconomic status, the higher the mortality from and hospital use due to coronary heart disease. For both genders, age-specific bypass operation rates were higher in the white-collar than blue-collar group for every level of coronary heart disease mortality (figure I). The

3 EUROPEAN JOURNAL OF PUBLIC HEALTH VOL NO. 4 curves for farmers were similar to those of the blue-collar group. In the comparison of surgery rates with annual risk of hospitalization due to coronary heart disease, the relative differences between social classes were smaller than in figure 1. In addition, the men's curve falls to the left of the women's curve, indicating a higher use of surgery among men than women at equal levels of risk for hospitalization (figure 2). In education categories the men's results were similar to diose for social class, but for women there were no systematic differences across the education groups between surgery rates and the 2 proxies for need. In the curves with risk of hospitalization as a proxy for need, the men's curves had the same shift to the left as for social classes compared to women's. Socioeconomic differences in bypass surgery in relation to need are summarized in table 2 using Kakwani's inequity indices. The mortality data were not available by income groups, thus the indices for disposable income were calculated only with risk of hospitalization as a proxy for need. All the index values were positive, indicating a distribution of operations clearly favouring higher socioeconomic groups. Rates for coronary surgery across hospital districts correlated with the proxies for need. The correlation coefficients between surgery rates and coronary heart disease mortality or hospitalization risk were 0.63 and The differences between social classes and education categories were greatest in hospital districts with the lowest Table 1 Age-adjusted rates for coronary artery bypass grafting and hospital utilization and mortality due to coronary heart disease (CHD) by social class, education and disposable income in Finland. and women aged years Social class Upper white-collar Lower white-collar Blue-collar Farmer Other >13 years- high years - intermediate <9 years low Disposable income Highest- 1st 2nd 3rd 4th Lowest - 5 th Social class Upper white-collar Lower white-collar Blue-collar Farmer Other >13 years- high years - intermediate <9 years - low Disposable income Highest - 1st 2nd 3rd 4th Lowest - 5th Coronary artery bypass grafting, % Cl Hospital utilization due to CHD, 1988 Annual risk of hospitalization Discharge rate Annual mortality from CHD,

4 Inequities in coronary bypass surgery CABQs per at risk, 1988 B-Whrte-coHar men ^White-collar men O White-collar women Slue-collar men -*- Blue-collar women Coronary heart disease mortality per at risk Annual risk ol hospitalization due to coronary heart disease per at risk Figure 2 Effect of gender and social class on the relationship between rates for coronary artery bypass grafting (CABG) and annual risk of hospitalization due to coronary heart disease (each point describes a 5 year age band across the age groups years) overall bypass surgery rates and clearly favoured the better-off of both genders (table 3). The socioeconomic gradients were milder in districts with higher overall operation rates. In fact for women, the gradient across education categories was reversed. Gender differences in bypass surgery tended to decrease with rising hospital district rates. In districts with the lowest surgery rates, the men's rate was 6 times higher than the women's, compared to the fourfold rate in districts with the highest rates. These findings were similar in all socioeconomic groups. Gender differences showed no similar changes across hospital districts for coronary heart disease mortality or risk of hospitalization. Previous studies in the UK and the USA have demonstrated socioeconomic '^and gender "discrepancies in the invasive treatment of coronary heart disease. These studies are not comparable to ours in terms of socioeconomic differences because they have used the socioeconomic structure of the patient's residential area as the indicator of social status. The gender difference in the use of coronary bypass operations may be larger in Finland than in the UK or the USA. In our study the male to female rate ratio in the year age group for coronary operations related to hospital discharges due to coronary heart disease was In the study by Petticrew et al. 16 the corresponding rate ratios in 2 areas of England were 1.39 and 1.47 and a similar study in the USA produced ratios of 1.63 and However, this disparity may result from gender differences in the severity of disease. In Finland the sex ratio in cardiovascular mortality is higher than in these 2 countries. 19 DISCUSSION In Finland in the late 1980s, a wide inequality between socioeconomic groups prevailed in the need-adjusted utilization of coronary artery bypass operations. The socioeconomic gradient in operation rates favouring the betteroff was more obvious for men and in hospital districts with a low supply of operations. These results were rather similar whether we applied mortality or hospital use as a proxy of need and for all socioeconomic indicators analysed, i.e. social class, education and disposable income. For women, the socioeconomic differences in operation rates were less clear, although the adjustment for need indicated that, for them too, the deployment of operations favoured the high socioeconomic groups. The less obvious trend may partly be explained by the concentration of coronary heart disease morbidity among older women of high social status, for whom the operation rates related to need indicator - regardless of social status were lower than for the younger age groups. There was some evidence of gender inequity, too. Needadjusted operation rates were similar in both genders when the need for operation was based on mortality. When overall hospital use due to coronary heart disease was used as the proxy for need, however, men's operation rates were higher. Gender differences diminished as the regional supply of operations rose. Table 2 Kakwani's inequity indices for the socioeconomic distribution of 1988 coronary artery bypass operations, using coronary heart disease mortality and 1988 annual risk of hospitalization due to coronary heart disease as proxies for need Proxy for need Annual risk of hospitalization due to coronary heart disease Coronary heart disease mortality Social classa and women _b and women b and women Disposable income a: Farmers and others excluded b: Mortality data not available by disposable income b Figure 1 Effect of gender and social class on the relationship between rates for coronary artery bypass grafting (CABG) and mortality from coronary heart disease (each point describes a 5 year age band across the age groups years)

5 EUROPEAN JOURNAL OF PUBLIC HEALTH VOL NO. 4 Our data covered over 90% of bypass operations performed in 1988 on patients aged years. Even if all the patients missing had been from lower socioeconomic groups, the main results would not have changed. Depending on the proxy for need, equalizing the operation rates for blue-collar and upper white-collar men in terms of relative need would have resulted in % more operations among blue-collar men. The data also excluded 110 bypass operations performed on Finnish patients abroad, but this probably reduced the socioeconomic differences observed in operation rates. Approximately half of these patients funded their own operations, implying that they were mainly from higher socioeconomic groups. Our study is based on coronary artery bypass rates in Unfortunately, more recent data on bypass operations or hospital use in socioeconomic groups have not been available. By 1993, the annual number of these operations had grown by 85% and coronary angioplasties had increased from 300 to l, This may have evened out discrepancies, as our findings on the regional supply of bypass surgery imply. Our conclusions on the existence of socioeconomic and gender inequities are susceptible to the validity of mortality and hospital utilization as indicators of coronary heart disease morbidity and the need for bypass operations. Both reflect the severe forms of the disease. A recent study showed that disparities in coronary heart disease mortality between time periods, regions or genders do not necessarily parallel differences in non-fatal morbidity. We assume, nevertheless, that mortality together with annual risk of hospitalization due to coronary heart disease provides a fairly satisfactory estimate of relative differences in morbidity across socioeconomic groups. For evaluating sex differences, our indicators of need are not necessarily as valid. As Ayanian et al. and Petticrew et al. 16 have pointed out, there are several factors, such as sex differences in severity of disease, anticipated risk and efficacy of operation or patients' preferences, which could account for sex differences in operation rates even after adjustment for need with our indicators. A more thorough assessment of sex inequities in coronary operations would require a study which made allowances for potential clinical and demographic confounding factors. When evaluating health policy it is important to judge if differences in access to bypass surgery are due to the structural factors in health services. In the Finnish health care system the role of private medicine is one such factor. Two private hospitals performed 20% of the bypass operations and another 5% were on private patients in public hospitals. However, this does not explain the socioeconomic disparities. Most operations in private hospitals were not performed on self-paying patients but were purchased by hospital districts because of the insufficient supply of coronary surgery in the public sector. Moreover, the socioeconomic gradients calculated separately for operations on regular patients in public hospitals also favoured high-status-groups. Private ambulatory services, on the other hand, may well have influenced the operation rates across socioeconomic groups. In practice, Finland has a two-tier system for physicians' visits. Patients of lower social status usually consult general practitioners at municipal health centres, Table 3 Age-adjusted rates (per 100,000 at risk) for coronary artery bypass grafting in 1988 by gender, social class, education and hospital district operation rate Level of hospital district operation rate Highest High Low Lowest Highest High Low Lowest White-collar Blue-collar Social class Farmer Relative rates (white-collar/ blue-collar) >10 years <9 years Relative rates (>10/<9) Relative rates, men/women Highest High Low Lowest

6 Inequities in coronary bypass surgery but in urban areas in particular the better-off tend to consult private specialists whose services are partly reimbursed by mandatory sickness insurance (on average by 34.3% in 1988). 21 ' 22 With coronary heart disease, the probability of being referred for angiography may have been higher at private practices than at health centres. If so, the explanation for socioeconomic disparities would be inadequate referral from health centres to hospital for coronary heart disease. Socioeconomic differences in referral may also result from doctors prioritizing the treatment of economically active patients, who will probably return to work after the operation.".24 j n tnis case manual workers could be discriminated against because of their difficulties in readjusting to their original employment. Many studies have explained socioeconomic differences in health care utilization by the ability of those with high social status to extract more benefit from health care services. Being more aware of alternatives, they are better at effective negotiation over treatments and more assertive about those they consider appropriate.^^treatment preferences among patient groups may also vary. In a US study, blacks refused recommended coronary bypass surgery 10% more often than whites.^ The increase in the supply of coronary revascularization procedures after the time of our study may have altered (probably decreased) socioeconomic and gender differences in the use of these procedures in Finland. However, the current health care system is basically similar to the one at the end of the 1980s. Thus, our study indicates that if the structure of the Finnish health care system could not guarantee equitable access to services in the 1980s, there is no reason to believe that the mechanisms allowing discrepancies in access have disappeared. The persistence of marked inequities is distressing in a health care system which, in principle, has no formal barrier to equal access and which has been claimed to be rather equitable in terms of the overall distribution of health services. 2 ' 21 A similar paradox seems to prevail in the British National Health Service, despite the equitable principles. 1-5 ' 16^ health care systems such as Finland's or Britain's, the socioeconomic and gender trends in the use of coronary bypass grafting and other high-technology treatments may largely derive from complex physicianpatient interactions. It would thus be somewhat difficult to eliminate these inequalities via general health care policy. 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