- Email: [email protected]
Cost benefits of targeting the Pneumococcal Vaccination Program to the elderly population in Taiwan
Cost benefits of targeting the Pneumococcal Vaccination Program to the elderly population in Taiwan Yeong-Hwang Chen, MD, MPH,a Guang-Yang Yang, MD, PhD,b Ching-Hui Loh, MD, PhD,a Saou-Hsing Liou, MD, PhD,c Wen-Lin Su, MD, MPH,d Shih-Hua Lin, MD,d and Chih-Chieh Chou, MD, MPHa Taipei, Taiwan, Republic of China
Background: Because of the continuing rise in pneumococcal vaccine costs and limits on funding of such costs, vaccination priorities in Taiwan were assessed. Methods: Data of a randomly selected sample of 200,448 people were analyzed to identify the highest risk groups. Patients were subgrouped on the basis of age and gender, and estimates were made of cumulative admissions, pneumonia recurrence rate, and associated costs of hospital care and medical treatment over the period 1997-2002 for each subgroup. Results: The per capita costs of medical treatment for pneumonia in those aged 65 years or above were found to be highest in those with chronic lung disease (US $19,906,086), heart disease (US $19,692,769), and diabetes mellitus (US $8,613,973). Conclusion: Elderly adults over age 65 years with these chronic diseases should be considered high-priority candidates for pneumococcal vaccination. (Am J Infect Control 2006;34:597-9.)
Taiwan was the first country in Asia to promote free influenza vaccination, especially for high-risk groups, and the rate of vaccination has risen dramatically from 9.95% in 1999 to 80% in 2003. By contrast, the importance and rate of pneumococcal polysaccharide vaccination in Taiwan remain relatively low, and its impact has not been assessed. Since the introduction of pneumococcal polysaccharide vaccine in 1999, the number of vaccinations has increased only modestly: 8000 in 1999, 15,000 in 2000, 17,000 in 2001, 16,000 in 2002, and 43,000 in 2003.1 Although evidence that pneumococcal vaccination of elderly adults is clinically protective remains uncertain, the US Centers for Disease Control and Prevention (CDC) recommends targeting those above 65 years of age for pneumococcal vaccination.2,3 Approximately 2.04 million individuals of the Taiwan population (22 million) are aged 65 years or above. From the Department of Family Medicine,a Tri-Service General Hospital, Nei-Hu; Yang-Min Universityb; the Department of Public Health,c National Defense Medical Center, Nei-Hu; and the Department of Internal Medicine,d Tri-Service General Hospital, Nei-Hu, Taipei, Taiwan, R.O.C. Reprint requests: Chih-Chieh Chou, MD, MPH, No. 325, Section 2, Chen-Kung Road, Department of Family Medicine, Tri-Service General Hospital, Nei-Hu, Taipei, Taiwan, 114, Republic of China. E-mail: [email protected]. 0196-6553/$32.00 Copyright ª 2006 by the Association for Professionals in Infection Control and Epidemiology, Inc. doi:10.1016/j.ajic.2006.02.009
To determine whether the program of pneumococcal vaccination of the elderly population should be expanded in Taiwan, we used the 1997-2002 data provided by the Bureau of National Health Insurance (BNHI) on hospital admissions because of pneumonia and associated medical costs to examine priorities for future extensive pneumococcal vaccination implementation.
METHODS A random sample of 200,448 people (97,690 female [F], 102,758 male [M], 9655 F aged $65 years, and 11,205 M aged $65 years) selected from 22 million people registered with the NHI in Taiwan (1/110 total population) were followed prospectively from 1997 for 6 years. The number of admissions and associated medical costs because of community-acquired pneumonia (CAP; defined as acquired pneumonia [ICD codes 460496] prompting an ambulatory care consultation within 7 days before hospital admission) were calculated from data provided by the BNHI. Ambulatory care expenditures by visits, inpatient expenditures by admissions, and details of inpatient orders were derived from the 1997-2002 NHI patient registration files. Patients were subgrouped on the basis of age and gender, and estimates were made of cumulative admissions, pneumonia recurrence rate, and associated costs of hospital care and medical treatment over the last 6 years for each subgroup. The influence of gender, age, and comorbidities on cumulative admissions; CAP recurrence rate; and associated costs of hospital care 597
598
Chen et al
Vol. 34 No. 9
Table 1. CAP admissions and costs stratified by age and sex (1997-2002) Sex
No. of inpatients
Costs per admission (US $)
SD (US $)
Mean length of stay (days)
SD
Accumulative admission rate (%)
0-2 3-5 6-19 20-34 35-49 50-64 65-110
F F F F F F F
81 172 158 42 52 57 181
373.8 617.4 631.7 795.1 1261.6 1918.3 3150.6
333.8 1617.2 2828.8 2077.4 4471.9 3717.6 6337.3
4.43 5.52 5.58 7.02 7.77 12.11 15.83
2.17 5.77 7.50 6.59 10.70 17.07 19.12
3.44 4.63 0.82 0.16 0.22 0.46 1.87
0-2 3-5 6-19 20-34 35-49 50-64 65-110
M M M M M M M
91 258 185 33 56 73 408
400.5 501.7 484.4 838.6 732.8 3076.1 3252.2
270.6 1127.1 1657.7 1278.9 1184.8 3382.9 5011.3
4.97 5.13 4.82 6.36 6.68 11.56 16.16
2.35 4.70 4.90 5.84 5.76 11.89 16.65
3.49 6.21 0.90 0.12 0.23 0.59 3.64
Age (yr)
M, male; F, female.
and medical treatment over the last 6 years were examined. Estimates of hospitalization risk were calculated by dividing the number of admissions of subjects in a particular subgroup over the 6-year study period by the total number of subjects within that subgroup.
year, with a cost of US $8,613,973. Similarly, 5729 CAP hospital admissions at a cost of US $19,692,769 would be expected among the 830,000 elderly with heart disease (Table 2).
DISCUSSION RESULTS Between 1997 and 2002, there were 6106 hospital admissions for pneumonia (1847 were for CAP) and US $13 million in NHI claims (US $2.8 million were for CAP) (Table 1). Each elderly female and male (ie, aged $65 years) had a 1.87% and 3.64%, respectively, yearly risk of being hospitalized for CAP. The average cost per hospital admission and the total cost for CAP in the elderly were approximately US $3221 and US $1,897,137, respectively. Chronic lung disease was the most common comorbid illness in these inpatients (405 patients), followed by heart disease (353 patients) (Table 2). The average cost of each hospital admission was highest for patients with heart disease (US $3437), followed by chronic lung disease (US $3028). The total cost of hospital admissions was highest in patients with chronic lung diseases (US $1,226,527) and second highest in those with heart disease (US $1,213,384) (Table 2). When the data are extrapolated to the entire elderly population of 2.03 million (aged 65 years and over) in Taiwan, the annual number of patients hospitalized for CAP would be 9559 and the annual cost of their hospitalization US $30,789,832. Of the 660,000 elderly patients with chronic lung disease, approximately 6573 would be hospitalized for CAP each year and their hospitalization cost more than US $19,906,086 annually. Of the 520,000 elderly diabetic patients, approximately 3181 would be hospitalized for CAP each
This is the first study of its kind conducted in Taiwan and one of the largest analyses based on the BNHI data. We conclude that targeting the pneumonia vaccination program to elderly patients with COPD, heart disease, or diabetes mellitus would yield medical care cost savings and possible overall reductions in the prevalence of CAP, although we have not shown evidence for the latter. Pneumonia and COPD (including asthma) are both leading causes of death in Taiwan, ranking seventh and ninth highest, respectively. The Taiwanese government has provided free influenza vaccination for high-risk populations since 1998, and the resulting vaccination rate remains one of the highest, not just among Asian countries, but also globally. Over the years, the total number of influenza vaccinations in Taiwan has exceeded 10 million and cost more than US $30 million. This high vaccination rate has been accompanied by a gradual decline in COPD and asthma deaths, but the number of deaths from pneumonia in elderly adults has continued to rise. Therefore, an important public health goal is to develop strategies to reduce pneumonia-related deaths in the elderly population.1 Epidemiologic data provided by the BNHI revealed that the most common causative agent for CAP in Taiwan is Streptococcus pneumoniae (21.8%). American studies in 1997 and 2000 showed an enormous annual disease burden because of Streptococcus pneumoniae, including more than a half million cases of pneumonia,
Chen et al
November 2006
599
Table 2. The prevalence of community-acquired pneumonia and associated hospitalization cost in US dollars in the randomly selected sample of elderly adults from the BNHI 1997-2002 database and extrapolations of this prevalence and cost to the total elderly population of Taiwan No. of inpatients diagnosed with CAP (1997-2002)
Number of subjects over age 65 years Age 651 years with chronic lung disease Age 651 years with diabetes mellitus Age 651 years with heart disease Age 651 on dialysis
Total cost of CAP hospitalizations (1997-2002)
Sample
Total
Average cost of each CAP hospitalization
589
9559
3220.9
1,897,137.5
30,789,832.4
405
6573
3028.5
1,226,527.7
19,906,086.3
196
3181
2707.9
530,756.1
8,613,973.0
353
5729
3437.4
1,213,384.0
19,692,769.0
9
146
3024.2
27,217.5
441,729.1
50,000 cases of septicemia, and 3000 cases of meningitis.2,4 Of the 2 groups most susceptible to streptococcal pneumonia (ie, children and elderly adults), elderly adults have a comparatively higher death rate. Many studies claim that pneumococcal vaccination can effectively prevent the occurrence of invasive pneumococcal disease (IPD)5-7 and is a cost-effective way to reduce acute exacerbations of COPD.8,9 In Taiwan, the rate of death because of IPD in elderly adults is approximately 42.5%. Although only approximately half of the CAP studies in Taiwan identified the relevant pneumonia causative agents and concluded that S pneumoniae is responsible for 20% to 22% of the cases,10 it is generally believed that the incidence rate of S pneumoniae-induced pneumonia is actually as high as 25% to 30% of the total CAP cases.11 We estimate that the annual cost of medical treatment of hospital-acquired pneumonia is US $238 million and CAP is US $52 million in Taiwan. The minimal reduction in death rates despite the high rates of influenza vaccination in Taiwan may be attributed to the extremely low rate of pneumococcal vaccination, and thus to failure to benefit from the synergy between the influenza and pneumococcal vaccinations as described by Nichol.12 Thus, we suggest that an additive benefit of this combination might be similarly demonstrated in Taiwan and serve as the basis for a future study of the effectiveness of pneumococcal vaccination here. The main limitation of this study is that no data actually suggest a protective effect of the vaccine in elderly adults. Nevertheless, other studies2,13 have suggested this on the basis of cost-effectiveness of vaccinating the elderly population. In conclusion, people $65 years of age with the above-mentioned chronic diseases should be considered high priority candidates for pneumococcal vaccination. Because of its potential to reduce the incidence or ameliorate the effects of CAP in targeted groups
Sample
Total
of elderly adults, pneumococcal vaccination also has potential economic benefit. References 1. Chen YH, Liou SH, Chou CC, Su WL, Loh CH, Lin SH. Influenza and pneumococcal vaccination of the elderly in Taiwan. Vaccine 2004;22: 2806-11. 2. CDC. Prevention of peumococcal disease: recommendations of the Advisory Committee on Immunization (ACIP). MMWR 1997; 46(RR-8):1-24. 3. CDC. Pneumococcal disease. In: Atkinson W, et al, editors. Epidemiology and prevention of vaccine-preventable diseases. 7th ed. Washington, DC: Department of Health and Human Services, Public Health Service; 2003. p. 205-17. 4. Feikin DR, Schuchat A, Kolczak M, Barrett NL, Harrison LH, Lefkowitz L, et al. Mortality from invasive pneumococcal pneumonia in the era of antibiotic resistance, 1995-1997. Am J Public Health 2000; 90:223-9. 5. Fedson DS. Pneumococcal vaccination in the United States and 20 other developed countries, 1981-1996. Clin Infect Dis 1998;26: 1117-23. 6. Artz AS, Reshler WB, Longo DL. Pneumococcal vaccination and revaccination of older adults. Clin Microbiol Rev 2003;16:308-18. 7. Christenson B, Hedlund J, Lundbergh P, Ortqvist A. Additive preventive effect of influenza and pneumococcal vaccines in elderly persons. Eur Respir J 2004;23:363-8. 8. Landesman SH, Smith PM, Schiffman G. Pneumococcal vaccine in elderly patients with COPD. Chest 1983;84:433-5. 9. Franzen D. Clinical efficacy of pneumococcal vaccination—a prospective study in patients with longstanding emphysema and/or bronchitis. Eur J Med Res 2000;29:537-40. 10. Lauderdale TL, Ho M, Chang FY. Etiology of community-acquired pneumonia in hospitalized adult patients in Taiwan. International Conference of Influenza and the Resurgence of SARS. Formosa Association, Taipei, Taiwan; 2003. 11. Hsueh PR, Wu JJ, Hsiue TR. Invasive Streptococcus pneumoniae infection associated with rapidly fatal outcome in Taiwan. J Formosa Med Assoc 1996;95:364-71. 12. Nichol KL. The additive benefits of influenza and pneumococcal vaccinations during influenza seasons among elderly persons with chronic lung disease. Vaccine 1999;17(Suppl 1):S91-3. 13. Ament A, Baltussen R, Duru G, Rigaud-Bully C, de Graeve D, Ortqvist A, et al. Cost-effectiveness of pneumococcal vaccination of older people: a study in 5 western European countries. Clin Infect Dis 2000;31:444-50.
Background: Because of the continuing rise in pneumococcal vaccine costs and limits on funding of such costs, vaccination priorities in Taiwan were assessed. Methods: Data of a randomly selected sample of 200,448 people were analyzed to identify the highest risk groups. Patients were subgrouped on the basis of age and gender, and estimates were made of cumulative admissions, pneumonia recurrence rate, and associated costs of hospital care and medical treatment over the period 1997-2002 for each subgroup. Results: The per capita costs of medical treatment for pneumonia in those aged 65 years or above were found to be highest in those with chronic lung disease (US $19,906,086), heart disease (US $19,692,769), and diabetes mellitus (US $8,613,973). Conclusion: Elderly adults over age 65 years with these chronic diseases should be considered high-priority candidates for pneumococcal vaccination. (Am J Infect Control 2006;34:597-9.)
Taiwan was the first country in Asia to promote free influenza vaccination, especially for high-risk groups, and the rate of vaccination has risen dramatically from 9.95% in 1999 to 80% in 2003. By contrast, the importance and rate of pneumococcal polysaccharide vaccination in Taiwan remain relatively low, and its impact has not been assessed. Since the introduction of pneumococcal polysaccharide vaccine in 1999, the number of vaccinations has increased only modestly: 8000 in 1999, 15,000 in 2000, 17,000 in 2001, 16,000 in 2002, and 43,000 in 2003.1 Although evidence that pneumococcal vaccination of elderly adults is clinically protective remains uncertain, the US Centers for Disease Control and Prevention (CDC) recommends targeting those above 65 years of age for pneumococcal vaccination.2,3 Approximately 2.04 million individuals of the Taiwan population (22 million) are aged 65 years or above. From the Department of Family Medicine,a Tri-Service General Hospital, Nei-Hu; Yang-Min Universityb; the Department of Public Health,c National Defense Medical Center, Nei-Hu; and the Department of Internal Medicine,d Tri-Service General Hospital, Nei-Hu, Taipei, Taiwan, R.O.C. Reprint requests: Chih-Chieh Chou, MD, MPH, No. 325, Section 2, Chen-Kung Road, Department of Family Medicine, Tri-Service General Hospital, Nei-Hu, Taipei, Taiwan, 114, Republic of China. E-mail: [email protected]. 0196-6553/$32.00 Copyright ª 2006 by the Association for Professionals in Infection Control and Epidemiology, Inc. doi:10.1016/j.ajic.2006.02.009
To determine whether the program of pneumococcal vaccination of the elderly population should be expanded in Taiwan, we used the 1997-2002 data provided by the Bureau of National Health Insurance (BNHI) on hospital admissions because of pneumonia and associated medical costs to examine priorities for future extensive pneumococcal vaccination implementation.
METHODS A random sample of 200,448 people (97,690 female [F], 102,758 male [M], 9655 F aged $65 years, and 11,205 M aged $65 years) selected from 22 million people registered with the NHI in Taiwan (1/110 total population) were followed prospectively from 1997 for 6 years. The number of admissions and associated medical costs because of community-acquired pneumonia (CAP; defined as acquired pneumonia [ICD codes 460496] prompting an ambulatory care consultation within 7 days before hospital admission) were calculated from data provided by the BNHI. Ambulatory care expenditures by visits, inpatient expenditures by admissions, and details of inpatient orders were derived from the 1997-2002 NHI patient registration files. Patients were subgrouped on the basis of age and gender, and estimates were made of cumulative admissions, pneumonia recurrence rate, and associated costs of hospital care and medical treatment over the last 6 years for each subgroup. The influence of gender, age, and comorbidities on cumulative admissions; CAP recurrence rate; and associated costs of hospital care 597
598
Chen et al
Vol. 34 No. 9
Table 1. CAP admissions and costs stratified by age and sex (1997-2002) Sex
No. of inpatients
Costs per admission (US $)
SD (US $)
Mean length of stay (days)
SD
Accumulative admission rate (%)
0-2 3-5 6-19 20-34 35-49 50-64 65-110
F F F F F F F
81 172 158 42 52 57 181
373.8 617.4 631.7 795.1 1261.6 1918.3 3150.6
333.8 1617.2 2828.8 2077.4 4471.9 3717.6 6337.3
4.43 5.52 5.58 7.02 7.77 12.11 15.83
2.17 5.77 7.50 6.59 10.70 17.07 19.12
3.44 4.63 0.82 0.16 0.22 0.46 1.87
0-2 3-5 6-19 20-34 35-49 50-64 65-110
M M M M M M M
91 258 185 33 56 73 408
400.5 501.7 484.4 838.6 732.8 3076.1 3252.2
270.6 1127.1 1657.7 1278.9 1184.8 3382.9 5011.3
4.97 5.13 4.82 6.36 6.68 11.56 16.16
2.35 4.70 4.90 5.84 5.76 11.89 16.65
3.49 6.21 0.90 0.12 0.23 0.59 3.64
Age (yr)
M, male; F, female.
and medical treatment over the last 6 years were examined. Estimates of hospitalization risk were calculated by dividing the number of admissions of subjects in a particular subgroup over the 6-year study period by the total number of subjects within that subgroup.
year, with a cost of US $8,613,973. Similarly, 5729 CAP hospital admissions at a cost of US $19,692,769 would be expected among the 830,000 elderly with heart disease (Table 2).
DISCUSSION RESULTS Between 1997 and 2002, there were 6106 hospital admissions for pneumonia (1847 were for CAP) and US $13 million in NHI claims (US $2.8 million were for CAP) (Table 1). Each elderly female and male (ie, aged $65 years) had a 1.87% and 3.64%, respectively, yearly risk of being hospitalized for CAP. The average cost per hospital admission and the total cost for CAP in the elderly were approximately US $3221 and US $1,897,137, respectively. Chronic lung disease was the most common comorbid illness in these inpatients (405 patients), followed by heart disease (353 patients) (Table 2). The average cost of each hospital admission was highest for patients with heart disease (US $3437), followed by chronic lung disease (US $3028). The total cost of hospital admissions was highest in patients with chronic lung diseases (US $1,226,527) and second highest in those with heart disease (US $1,213,384) (Table 2). When the data are extrapolated to the entire elderly population of 2.03 million (aged 65 years and over) in Taiwan, the annual number of patients hospitalized for CAP would be 9559 and the annual cost of their hospitalization US $30,789,832. Of the 660,000 elderly patients with chronic lung disease, approximately 6573 would be hospitalized for CAP each year and their hospitalization cost more than US $19,906,086 annually. Of the 520,000 elderly diabetic patients, approximately 3181 would be hospitalized for CAP each
This is the first study of its kind conducted in Taiwan and one of the largest analyses based on the BNHI data. We conclude that targeting the pneumonia vaccination program to elderly patients with COPD, heart disease, or diabetes mellitus would yield medical care cost savings and possible overall reductions in the prevalence of CAP, although we have not shown evidence for the latter. Pneumonia and COPD (including asthma) are both leading causes of death in Taiwan, ranking seventh and ninth highest, respectively. The Taiwanese government has provided free influenza vaccination for high-risk populations since 1998, and the resulting vaccination rate remains one of the highest, not just among Asian countries, but also globally. Over the years, the total number of influenza vaccinations in Taiwan has exceeded 10 million and cost more than US $30 million. This high vaccination rate has been accompanied by a gradual decline in COPD and asthma deaths, but the number of deaths from pneumonia in elderly adults has continued to rise. Therefore, an important public health goal is to develop strategies to reduce pneumonia-related deaths in the elderly population.1 Epidemiologic data provided by the BNHI revealed that the most common causative agent for CAP in Taiwan is Streptococcus pneumoniae (21.8%). American studies in 1997 and 2000 showed an enormous annual disease burden because of Streptococcus pneumoniae, including more than a half million cases of pneumonia,
Chen et al
November 2006
599
Table 2. The prevalence of community-acquired pneumonia and associated hospitalization cost in US dollars in the randomly selected sample of elderly adults from the BNHI 1997-2002 database and extrapolations of this prevalence and cost to the total elderly population of Taiwan No. of inpatients diagnosed with CAP (1997-2002)
Number of subjects over age 65 years Age 651 years with chronic lung disease Age 651 years with diabetes mellitus Age 651 years with heart disease Age 651 on dialysis
Total cost of CAP hospitalizations (1997-2002)
Sample
Total
Average cost of each CAP hospitalization
589
9559
3220.9
1,897,137.5
30,789,832.4
405
6573
3028.5
1,226,527.7
19,906,086.3
196
3181
2707.9
530,756.1
8,613,973.0
353
5729
3437.4
1,213,384.0
19,692,769.0
9
146
3024.2
27,217.5
441,729.1
50,000 cases of septicemia, and 3000 cases of meningitis.2,4 Of the 2 groups most susceptible to streptococcal pneumonia (ie, children and elderly adults), elderly adults have a comparatively higher death rate. Many studies claim that pneumococcal vaccination can effectively prevent the occurrence of invasive pneumococcal disease (IPD)5-7 and is a cost-effective way to reduce acute exacerbations of COPD.8,9 In Taiwan, the rate of death because of IPD in elderly adults is approximately 42.5%. Although only approximately half of the CAP studies in Taiwan identified the relevant pneumonia causative agents and concluded that S pneumoniae is responsible for 20% to 22% of the cases,10 it is generally believed that the incidence rate of S pneumoniae-induced pneumonia is actually as high as 25% to 30% of the total CAP cases.11 We estimate that the annual cost of medical treatment of hospital-acquired pneumonia is US $238 million and CAP is US $52 million in Taiwan. The minimal reduction in death rates despite the high rates of influenza vaccination in Taiwan may be attributed to the extremely low rate of pneumococcal vaccination, and thus to failure to benefit from the synergy between the influenza and pneumococcal vaccinations as described by Nichol.12 Thus, we suggest that an additive benefit of this combination might be similarly demonstrated in Taiwan and serve as the basis for a future study of the effectiveness of pneumococcal vaccination here. The main limitation of this study is that no data actually suggest a protective effect of the vaccine in elderly adults. Nevertheless, other studies2,13 have suggested this on the basis of cost-effectiveness of vaccinating the elderly population. In conclusion, people $65 years of age with the above-mentioned chronic diseases should be considered high priority candidates for pneumococcal vaccination. Because of its potential to reduce the incidence or ameliorate the effects of CAP in targeted groups
Sample
Total
of elderly adults, pneumococcal vaccination also has potential economic benefit. References 1. Chen YH, Liou SH, Chou CC, Su WL, Loh CH, Lin SH. Influenza and pneumococcal vaccination of the elderly in Taiwan. Vaccine 2004;22: 2806-11. 2. CDC. Prevention of peumococcal disease: recommendations of the Advisory Committee on Immunization (ACIP). MMWR 1997; 46(RR-8):1-24. 3. CDC. Pneumococcal disease. In: Atkinson W, et al, editors. Epidemiology and prevention of vaccine-preventable diseases. 7th ed. Washington, DC: Department of Health and Human Services, Public Health Service; 2003. p. 205-17. 4. Feikin DR, Schuchat A, Kolczak M, Barrett NL, Harrison LH, Lefkowitz L, et al. Mortality from invasive pneumococcal pneumonia in the era of antibiotic resistance, 1995-1997. Am J Public Health 2000; 90:223-9. 5. Fedson DS. Pneumococcal vaccination in the United States and 20 other developed countries, 1981-1996. Clin Infect Dis 1998;26: 1117-23. 6. Artz AS, Reshler WB, Longo DL. Pneumococcal vaccination and revaccination of older adults. Clin Microbiol Rev 2003;16:308-18. 7. Christenson B, Hedlund J, Lundbergh P, Ortqvist A. Additive preventive effect of influenza and pneumococcal vaccines in elderly persons. Eur Respir J 2004;23:363-8. 8. Landesman SH, Smith PM, Schiffman G. Pneumococcal vaccine in elderly patients with COPD. Chest 1983;84:433-5. 9. Franzen D. Clinical efficacy of pneumococcal vaccination—a prospective study in patients with longstanding emphysema and/or bronchitis. Eur J Med Res 2000;29:537-40. 10. Lauderdale TL, Ho M, Chang FY. Etiology of community-acquired pneumonia in hospitalized adult patients in Taiwan. International Conference of Influenza and the Resurgence of SARS. Formosa Association, Taipei, Taiwan; 2003. 11. Hsueh PR, Wu JJ, Hsiue TR. Invasive Streptococcus pneumoniae infection associated with rapidly fatal outcome in Taiwan. J Formosa Med Assoc 1996;95:364-71. 12. Nichol KL. The additive benefits of influenza and pneumococcal vaccinations during influenza seasons among elderly persons with chronic lung disease. Vaccine 1999;17(Suppl 1):S91-3. 13. Ament A, Baltussen R, Duru G, Rigaud-Bully C, de Graeve D, Ortqvist A, et al. Cost-effectiveness of pneumococcal vaccination of older people: a study in 5 western European countries. Clin Infect Dis 2000;31:444-50.