Response to Letter by Khang and Lynch

LETTER Response to Letter by Khang and Lynch Dear Editors: Unlike our previous study (1), Khang and Lynch suggested that the economic crisis in South Korea was not related with increased mortality. We used monthly mortality data from 1995 to 1999, and Khang and Lynch’s used annual mortality data from 1990 to 2002. However, these two analyses are basically based on same data source. Khang and Lynch criticized our study with some issues in data analyses and interpretations. But their arguments are not likely based on sound evidence, and have limitations as follows. First, Khang and Lynch questioned the accuracy of our estimates, which were a 15.5% increase in cardiovascular mortality and 44.4% increase in ischemic heart disease mortality due to the economic crisis. The grounds for their assertion were that there was no special report on mortality increase from the Korean National Statistical Office (KNSO), and that the mortality increase was too great to be interpreted as an effect of economic crisis. These points do not seem reasonable. The mission of KNSO is to produce accurate and representative statistics. The KNSO might not interpret important changes in their statistics, and might not detect causes of the changes. Some other factors besides economic crisis might contribute to the excess deaths. But the size of excess deaths itself does not seem to be a sound reason for their suspicion on our estimates. Second, Khang and Lynch said that all-cause mortality did not increase after the economic crisis. Their interpretation was based on the increase of life expectancy at birth during the period. However, considering the increasing trend of the life expectancy at birth (72.81 in 1993), we could not regard it as appropriate that the life expectancy after the economic crisis has increased (2). Also, the increase of mortality does not always lead to the decrease of life expectancy. They also insist that the economic crisis had

no effect on the cardiovascular disease mortality and cerebrovascular disease mortality, because mortality had decreased continuously during the economic crisis. However, our analyses were based on the excess deaths when the increasing trends of mortality were considered. Table 1 shows the annual all-cause mortality, cardiovascular disease mortality, and mortality from ischemic heart disease (2). Considering the increasing trends, it can be judged that all mortality has increased relatively after the economic crisis. Interpretation of data without considering the increasing trends may lead to invalid conclusions. Third, Khang and Lynch pointed out that alcohol consumption decreased during the economic crisis. As Khang and Lynch pointed out, alcohol intake may affect mortality from cardiovascular disease. However, the total amount of alcohol consumed did not inform us of the pattern of individual alcohol intake. In addition, alcohol intake is not positively related with cardiovascular mortality in most observational studies. The risk factors of the cardiovascular diseases are smoking, blood pressure, and total cholesterol, rather than alcohol consumption in Korean men (3). Jee et al. also showed that the population attributable risk for cardiovascular disease was 35% from hypertension (3). Thus, the decrease of alcohol intake may not lead to a decrease in mortality. In a previous study (4), we suggested that an economic crisis was likely to increase the unemployment rate, reduce the household income, restrict access to medical services, and increase stress, and thus affect hypertension and cardiovascular morbidity. Chung Mo Nam, PHD Hanjoong Kim, MD, PHD Department of Preventive Medicine and Public Health Yonsei University College of Medicine Seoul, Korea

TABLE 1. Annual crude mortality of all-cause, cardiovascular disease, and ischemic heart disease in South Korea Before economic crisis

All-cause Cardiovascular disease Ischemic heart disease

After economic crisis

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

549.1 163.9 10.4

547.7 157.0 11.6

529.2 156.0 12.5

516.1 156.0 13.3

530.2 158.3 12.6

526.3 138.6 13.1

516.1 127.0 13.0

518.3 121.0 13.8

517.4 123.7 16.3

522.7 122.0 18.5

Unit: per 100,000.

Ó 2005 Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010

1047-2797/05/$–see front matter doi:10.1016/j.annepidem.2004.09.009

AEP Vol. 15, No. 7 August 2005: 538–539

REFERENCES

Nam and Kim LETTER

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TableID=MT_ETITLE&TitleID=B&FPub=4&UserID=. Accessed September 14, 2004.

1. Kim H, Song YJ, Yi JJ, Chung WJ, Nam CM. Changes in mortality after the recent economic crisis in South Korea. Ann Epidemiol. 2004;14: 442–446.

3. Jee SH, Suh I, Kim IS, Appel LJ. Smoking and atherosclerotic cardiovascular disease in men with low levels of serum cholesterol. JAMA. 1999;282:2149–2155.

2. National Statistical Office of Korea. Statistical Database. Available at: http://kosis.nso.go.kr/cgi-bin/SWS_1021.cgi?KorEng=2&A_UNFOLD=1&-

4. Kim H, Chung WJ, Song YJ, Kang DR, Yi JJ, Nam CM. Changes in morbidity and medical care utilization after the recent economic crisis in the Republic of Korea. Bull World Health Organ. 2003;81:567–572.