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Volume 12, Number 1—January 2006
Research

Economics of Neuraminidase Inhibitor Stockpiling for Pandemic Influenza, Singapore

Vernon J. Lee*Comments to Author , Kai Hong Phua†, Mark I. Chen*, Angela Chow‡, Stefan Ma‡, Kee Tai Goh‡, and Yee Sin Leo*
Author affiliations: *Tan Tock Seng Hospital, Singapore; †National University of Singapore, Singapore; ‡Ministry of Health, Singapore

Main Article

Table 1

Input variables used in analysis*†

Input variables Age ranges, y
<19 20–64 >65 Sources
Average age 10 40 73 16
Population, ×1,000 persons 999.2 2,962.5 278.6 16
Low risk, % 90 89.7 63.3
High risk, %‡ 10 10.3 36.7 17–20
Baseline influenzalike illness rate, cases/wk 7,686 19,940 750 2,21
Influenza clinical attack rate, % (range) 30 (10–50) 30 (10–50) 30 (10–50) 4,13,22,23
Case-fatality rate/100,000§ Ministry of Health 4,13,24,
Low risk 5 (1–12.5) 6 (1–9) 340 (28–680)
High risk 137 (12.6–765) 149 (10–570) 1,700 (276–3,400)
Earnings lost per death, $¶ 1,909,092 1,780,027 187,301 16,25
Hospitalization rate/100,000 infected# Ministry of Health
Low risk 210 (42–525) 72 (12–108) 1,634 (135–3,268)
High risk 210 (100–1,173) 234 (16–895) 2,167 (352–4,334)
Average length of hospital stay, d 3.88 (2.3–9.2) 4.61 (3.2–11.8) 6.20 (4.6–13.4) 13,24,26
Average additional days lost 2 (1–3) 2 (1–3) 2 (1–3) Local physicians
Hospital cost, $/d 342 342 342 Ministry of Health
Value of 1 lost day, $** 108 166/108 108 Ministry of Health, 25
Outpatient
Days lost from outpatient influenza 3 (1–5) 3 (1–5) 3 (1–5) 9,13,23,27
Consultation and outpatient treatment cost, $ 40 40 40 Local physicians
Value of 1 lost day, $** 108 166 108 Ministry of Health 25,
Treatment with oseltamivir
Sought early medical care, % 70 (50–90) 70 (50–90) 70 (50–90) 13,28
Case-fatality rate reduction, % 70 (50–90) 70 (50–90) 30 (20–90) 24,29
Hospitalization rate reduction, % 60 (50–90) 60 (50–90) 30 (20–90) 11,24
Lost days gained, d 1.0 (0.1–2.0) 1.0 (0.1–2.0) 1.0 (0.1–2.0) 7,9,24,28
Treatment cost, $ per course 31 31 31 Ministry of Health
Prophylaxis with oseltamivir
Efficacy of prophylaxis, % 70 (50–90) 70 (50–90) 70 (50–90) 12,30
Immunity after prophylaxis, % 35 (20–50) 35 (20–50) 35 (20–50) 12,30
Prophylaxis cost, $/wk 21.7 21.7 21.7 Ministry of Health
No. stockpile cycles to pandemic 2.25 (1–3.5) 2.25 (1–3.5) 2.25 (1–3.5) 31,32
Pandemic duration, wk 12 (6–24) 32–34
Treatment stockpile, % of population†† 10–100
Prophylaxis stockpile, wk†† 2–24

*All healthcare costs are in 2004 Singapore dollars and were compounded by using the consumer price index for Singapore (16).
†Base-case values are given with the range used for analysis given in parentheses, where applicable. Input variables were modeled as triangular distributions centered on base values; minimum and maximum values are given by extreme values in ranges.
‡High risk includes asthma, chronic obstructive pulmonary disease, heart disease, and diabetes patients.
§Based on deaths among those with clinical influenza.
¶Average present value of future earnings lost per death of a person of average age in the age group.
#Rate is based on hospitalizations among those with clinical influenza. Ranges were calculated based on a factor of the base cases versus the death rate.
**$166 for lost work day, $108 for unspecified days lost (taking care of ill child or elderly person), and additional days lost after hospitalization.
††The treatment and prophylaxis stockpiles are decision variables, and the analyses were performed for a range of values to determine the preferred outcomes.

Main Article

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Main Article

1"Dominate" is a term used in cost-effectiveness analyses and refers to a strategy that is both more efficacious and less costly than another strategy.

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