MORTALITY OF DOCTORS: DO DOCTORS BENEFIT FROM THEIR MEDICAL KNOWLEDGE?

84 TABLE I-OCCUPATIONAL GROUPS USED IN THE STUDY

Occupational Medicine MORTALITY OF DOCTORS: DO DOCTORS BENEFIT FROM THEIR MEDICAL

KNOWLEDGE? MARKKU M. NURMINEN ARJA H. RIMPELÄ PEKKA O. PULKKINEN MATTI K. RIMPELÄ TAPANI VALKONEN

Departments of Public Health and Sociology, University of Helsinki, Helsinki, Finland Official population and mortality statistics show that overall mortality of male doctors in Finland in 1971-80 was lower than that of all economically active men. Doctors had lower death rates from cardiovascular disease, tumours, other diseases, causes of death amenable to medical interventions, and accidents and violence, but not suicide. Except for tumours, mortality of male doctors was at the same level or higher than that of men in other professions. Risk of suicide was twice as high for male doctors as for other professions. The numbers of women doctors were too small for firm conclusions about their mortality to be drawn. It is concluded either that doctors do not use their professional knowledge and skills in a way that reduces their own mortality risk or that they are exposed to occupational hazards that cancel out such an effect. Possible hazards are more likely to be mental than physical or chemical.

Summary

INTRODUCTION

STUDIES from several countries have shown that the overall mortality of doctors is lower than that of the general population.l-6 In Western countries doctors have a high social status, high level of education, and usually aboveaverage income. Thus they belong to upper socioeconomic groups, whose mortality is low.7-9 But such comparisons reveal little about the effects of occupational factors on the health of doctors-in particular, whether doctors’ special knowledge and skills have a beneficial effect on their mortality. To identify those specific effects we have compared mortality, in the 1970s, in doctors and in other occupational groups most similar to them in socioeconomic and educational status. The comparison covers all Finnish persons in each occupational group residing in the country and is based on the linkage of two computerised data files. METHODS

This study is based on data files compiled by the Central Statistical Office of Finland for a more extensive study on occupational mortality.8 The data files include information obtained from the population census of Finland in 1970 and from cause-of-death statistics from 1971 to 1980. The Central Statistical Office of Finland linked these two computerised data bases by means of a personal identification code given to everybody living in Finland. There were 23% mismatches for men and 1.8% for women, resulting mainly from inadequate coverage in the population census. The population census recorded the occupation of each economically active person living in the country on Dec 31, 1970, according to the nomenclature of occupations.10 For the present study those aged 30 to 64 at the time of the census were drawn from the files, 30 being approximately the lower age limit of entry into some occupational groups.

The following criteria were used in the selection of the comparison groups: (i) high social status, (ii) all or most members had a degree, and (iii) numbers in the group were adequate (at least 1500). The occupational groups studied are shown in table i. Because of the small number of women in several occupations, only five comparison groups for women were found. Although all Finns in the selected occupations were included in the study, the number of deaths in several occupations was so small that the comparison groups were combined as "other professionals". The total economically active population of the same sex was used as an additional reference population. The principle applied in occupational classification was to combine similar activities irrespective of education, occupational status or position, or area of activity.8 Thus physicians in clinical practice were recorded as doctors, and physicians who worked as research-workers or in administration were classified accordingly. Mortality in the study population was followed from 1971 to 1980. Deaths were classified according to the 8th revision of the International Classification of Diseases (ICD): (1) all causes; (2) tumours (140-239); (3) cardiovascular diseases 390-458; (4) other diseases; (5) suicides and suspected suicides (E950-959, E980-989); (6) other accidents, poisonings, and violence (E807-949, E960999) ; and (7) causes of death amenable to medical interventions, as defined by Poikolainen and Eskola.ll Male and female age-standardised death rates were calculated the population of doctors as the standard. Agestandardised rates are reported as a comparative mortality figure (CMF), in which the mortality of the standard population is taken as 100." In the calculation of the person-years at risk, emigration could not be taken into account, but its effect on the accrued person-years is negligible. The 95 % confidence interval (CI) for the mortality index was calculated on the assumption that incidences followed a poisson probability model. 13 The statistical significance of CMF was assessed with a normally distributed test statistiC.13

directly, with

RESULTS (TABLE II)

All-cause mortality of male doctors was significantly lower than that of all economically active men (p 0-004) but higher than that of other professionals. In comparisons of doctors with other groups individually, only the managing directors (CMF = 101, CI 91-110) and those in legal work (CMF = 104, CI 88-119) had as high a mortality as doctors. The death rate of architects and engineers was significantly lower (CMF=77, CI 70-85) than that of doctors. The pattern in cardiovascular mortality was similar to that of all-cause mortality: the rate for doctors was lower than =

85 TABLE II-COMPARATIVE MORTALITY RATES AND

95 %

CONFI-

DENCE INTERVALS FOR DOCTORS, OTHER PROFESSIONS, AND TOTAL ECONOMICALLY ACTIVE POPULATION WITH DOCTORS AS THE STANDARD

(= 100)

peer groups and all economically active but the differences were not significant. Because of women, the small number of deaths, cause-specific death rates were not calculated.

occupational

DISCUSSION

Figures in parentheses are no of deaths in *p<005,tp<001;tp<0’001.

The material of this study consisted of all Finns in the selected occupations and all deaths registered among them during the 10-year follow-up period. Possible biases caused by drawing a sample are thus excluded. When the computerised data bases (the population census of 1970 and the death register) were linked by the Central Statistical Office of Finland with the aid of a personal identification code, there were only 2% mismatches. This evinces the reliability of the Finnish record linkage system. Since the number of person-years in the occupation (denominator) and the occupation for the dead persons (numerator) came from the same data base, bias in the material that could seriously affect the results is highly improbable. Although emigration could not be taken into account in the calculation of person-years, its effect is too small to distort the results. Our finding of lower overall mortality of male doctors than of all economically active men agrees with the results from other countries.l-4 The results of the Danish and Norwegian mortality studies were compatible with those of our own study, but doctors were combined with dentists in the Norwegian study6 and with dentists and veterinarians in the Danish study.5 The lower mortality of doctors derives from their high socioeconomic status and is not specific to their occupation. High socioeconomic groups differ from other groups in several ways that affect health: they have a lower smoking rate, healthier eating habits, better economic status, and better working conditions.

1971-80.

that of the general population but higher than that of the other professionals. The differences were not statistically significant. A comparison with individual occupational groups showed that male doctors had the highest mortality of all from cardiovascular diseases. Cancer death-rates were significantly lower in doctors and also than in all economically active men (p<0-001) lower than in other professionals, although the last difference was not statistically significant. Only one occupational group (chemical, physical, and biological workers) had lower death rates from cancer than doctors. Mortality from diseases other than cancer or cardiovascular diseases did not differ between doctors and other professionals but was somewhat lower among doctors than in economically active men. Male doctors had

higher suicide rate than the general (p = 0-02). Only men in legal work had as high a suicide rate as doctors (CMF = 101, CI 43-159). Mortality from other accidents and violence was also higher in doctors than in other professionals but lower than in all economically active men. Only managing directors (CMF = 114, CI 84-143) and officers in military service (CMF = 228, CI 142-315) had higher mortality

population

or

a

Because of their high socioeconomic status, male doctors would be expected to have lower mortality from cardiovascular diseases than all economically active males. We found a small but non-significant difference in this direction. However, doctors’ mortality from cardiovascular diseases was slightly higher than that of their occupational peer groups.

peer groups

from accidents and violence than doctors.

Mortality

The mortality of male doctors was as high as or higher than that of other professionals. Again, this result is consistent with the results of other studies.2,5,14 Our results suggest that doctors may have some special occupational risks, which raise their mortality. Stress, suicide, alcoholism, and drug use have been widely discussed as occupational hazards of doctors. 11-17 Physical and chemical factors, especially radiation and anaesthetic gases, have also been discussed as possible occupational hazards.18-2o

from

causes

of death amenable

to

medical

interventions was lower in doctors than in all economically active men. These causes were somewhat higher in doctors than in their peers, but the differences were not statistically

significant. Only 27 women doctors died during the 10-year followup. Their mortality was somewhat higher than that of

In a previous Finnish study, covering the years 1953-72, cardiovascular mortality in doctors was similar to that of the general population, which included also economically inactive persons with high death rates. A study in Connecticut also found cardiovascular mortality to be somewhat higher in male doctors than in lawyers,14 and another American study concerning the years 1949-51 found higher cardiovascular mortality among doctors than in the general population.21 However, studies from Norway and Denmark do not show much difference between doctors (together with dentists and veterinarians in two studies5,6) and other occupational or educational groups with high socioeconomic status.5,6.22 Thus it is difficult to draw any global conclusion about doctors’ mortality from cardiovascular diseases.

86

mortality among male doctors was very low in comparison with all economically active men and also lower, although not significantly so, than that of other professionals. The first result is expected on the basis of Cancer

lower cancer incidence in upper social groups23 and has been found in previous studies.2,4-6 The lower cancer mortality of doctors than occupational peer groups may be due to chance or may reflect better health care and earlier diagnosis (and therefore better prognosis) of cancer in doctors. Healthier lifestyle is an unlikely explanation, since Finnish doctors smoke as much as other well-educated groupS.24 In a Swedish study doctors had a lower mortality from

respiratory cancer than academics, although not significantly.25 In a Danish study doctors (with dentists and veterinarians) had lower cancer mortality than most groups.5 On the other hand, McCrea Cumen et al14 found no difference in cancer mortality between doctors and lawyers in Connecticut, and in a Norwegian study doctors and dentists combined had lower cancer mortality than the general male population, but not lower than that of their peers.6 Radiation and other carcinogens seem to contribute little to total cancer mortality in doctors. In some studies the suicide rate of male doctors has been found to be no higher than that of the general population .4,16,11 In studies in Norway and Denmark, however, doctors (combined with dentists or veterinarians) had a higher suicide rate than all economically active men.5,6 Our study, too, showed a somewhat higher rate of suicides among doctors, but the difference was not significant.

be tentative. The overall mortality of women doctors was, however, higher than that of women in other professions and was not lower than that of all economically active women.

only

In our study the mortality of doctors was not found to be lower than that of other professions. This suggests either that doctors do not use their professional knowledge and skills in a way that lowers their own mortality or that other occupation-related factors cancel out any benefit. The high risk of suicide points to mental strain as a major occupational hazard for doctors. We thank the Central Statistical Office of Finland for providing the data for this study.

Correspondence should be addressed to A. H. R., Department of Public Health, University of Helsinki, Haartmaninkatu 3, 00290 Helsinki 29, Finland.

REFERENCES

FG, Martin LW. Physician mortality, 1949-1951 J Am Med Assoc 1956; 162: 1462-68. 2. Registrar General. Decennial Supplement, England and Wales, 1961. Occupational mortality tables. London: HM Stationery Office, 1971. 3. Williams SV, Munford RS, Colton T, Murphy DA, Poskanzer DC Mortality among physicians. A cohort study J Chron Dis 1971; 24: 393-401. 4. Asp S, Hernberg S, Collan Y. Mortality among Finnish doctors, 1953-1972 Scand J Soc Med 1979, 7: 55-62. 5. Andersen O. Dodelighed og erhverv 1970-80 (Occupation and mortality) Kobenhavn. Danmarks Statistik, 1985, Statistiske Undersogelser n:o 41. (In 1 Dickinson

Danish.) Borgan J-K, Kristofersen LB. Mortality by occupation and socio-economic group in Norway 1970-1980. Oslo- Central Bureau of Statistics of Norway, 1986. Statistiske analyser 56. 7. Syme SL, Berkman LF Social class, susceptibility and sickness AmJ Epidemiol 1976,

6.

Compared with other professionals, however, doctors showed a doubled risk of suicide. A doubled risk was also found in a Swedish study22 in which male doctors were compared with academics. Data from England and Wales have shown a higher suicide rate for male doctors than all other professional groups except pharmacists.Zb Norwegian and Danish mortality studies are in accordance with these results.5,6 Differentiation between suicide, accident, poisoning, and violence as a cause of death is often difficult, and suicide might sometimes be falsely, even deliberately, classified as an accident-and even differently in different occupational groups. A probable bias in doctors is that they are unwilling to classify the death of a colleague as suicide but prefer an accident. In our study mortality of male doctors from other accidents, poisonings, and violence was lower than that of all economically active males, as expected from the lower mortality from these causes in higher socioeconomic groups.8 But mortality from these causes was higher, although not significantly so, among doctors than among occupational peer groups: the real suicide rate in doctors might be even higher. Violent causes of death seem to be somewhat more common in male doctors than in other professionals. Similar results have been obtained from Connecticut,14 England and Wales,26 Norway,6 and Denmark,s Causes of death amenable to medical intervention might be expected to be lower in doctors than in their occupational peer groups or the general population, because doctors are expected both to know when to seek medical help and to receive better health care than other people. Our result does not support that idea. Because there

relatively few women doctors in the early 1970s, conclusions about mortality in that group can were

104: 1-8. 8. Sauli H.

Occupational mortality in 1971-75. Helsinki: Central Statistical Office of Finland, 1979, studies no 54. (In Finnish with English summary.) 9. Townsend P, Davidson N. Inequalities in health: The Black report. Harmondsworth Penguin Books Ltd, 1982 1970 Occupation and social position Helsinki Central Statistical Office of Finland, 1974; Official statistics VI C:104, Helsinki, 1974. 11. Poikolainen K, Eskola J. The effect of health services on mortality: Decline in death rates from amenable and non-amenable causes in Finland, 1969-81. Lancet 1986; i. 10.

Population census

199-202. 12. Silcock H. The comparison of occupational

mortality rates Population Stud 1959; 13: 183-92. 13. World Health Organisation. Manual of mortality analysis Geneva: WHO, 1980. 14. McCrea Cumen MG, Turgeon LR, Valanis B, Skovron ML, Varma AAO, Fleiss JL. Cancer in Connecticut physicians and lawyers: a study by birth cohorts (1875-1939). Connecticut Med 1985; 49: 729-37. 15. Keeve JP Physicians at risk Some epidemiologic considerations of alcoholism, drug abuse, and suicide. J Occup Med 1984; 26: 503-08 16. Roy A. Suicide in doctors. Psychiatr Clin North Am 1985, 8: 377-87. 17. May HJ, Revicki DA. Professional stress among family physicians. J Fam Pract 1985, 20: 165-71 18. Matanoski GM, Sartwell P, Elliot E, Tonascia J, Stemberg A. Cancer risks in radiologists and radiation workers. In Boice JD Jr, Fraumeni JF Jr, eds. Radiation carcinogenesis: Epidemiology and biological significance New York: Raven Press, 1984: 83-96. 19. Logue JN, Barrick MK, Jessup GL Mortality of radiologists and pathologists in the radiation registry of physicians J Occup Med 1986; 28: 91-99. 20. Goldstein PD, Paz J, Giuffnda JG, Palmes ED, Ferrand EF. Atmospheric derivatives of anesthetic gases as a possible hazard to operating-room personnel Lancet 1976; ii 235-37. 21. Goodman LJ The longevity and mortality of American physicians, 1969-1973 Millbank Meml Fund Quart 1975; 53: 353-75 22. Ametz B, Hone L-G, Hedberg A, Theorell T, Allander E, Malker H Physicians’ mortality pattern in ischemic heart disease and suicide. Result from a long-term prospective as well as a retrospective study Stockholm Laboratory for Clinical Stress Research, 1986; Stress Research Reports no 185. (In Swedish, English summary.) Rimpela A, Pukkala E. Socioeconomic status, education and the incidence of cancer. Sosiaalilaaketieteellinen aikakauslehti. J Soc Med 1984; 21: 61-75. (In Finnish, English summary.) 24. Byckling T, Rimpela M. Laakareiden tupakointitavat muuttuneet. (The changing smoking habits among Finnish doctors.) Suomen Laakarilehti 1985; 40: 2205-10 (In Finnish.) 25. Ametz B, Allander E, Hedberg A, Horte L-G, Malker H, Theorell T. Svenska lakares dodlighetsmonster relaterat till ovnga akademikergrupper. (Mortality pattern of

23

Swedish doctors in relation to other academics. Data based on death register ) Svenska Lakaresallskapets Handlingar Hygiea 1985; 94 (Hafte 6): 267. (In Swedish) 26. Sakinofsky I Suicide in doctors and wives of doctors Can Fam Phys 1980; 26: 837-44