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The relationship between tuberculosis and influenza death during the influenza (H1N1) pandemic from 1918-19.

Oei W, Nishiura H - Comput Math Methods Med (2012)

Bottom Line: The present study aimed to develop a formal hypothesis: tuberculosis (TB) was associated with the W-shaped influenza mortality from 1918-19.Analyzing the data (i), we found that the W-shaped pattern was not only seen in mortality but also in the age-specific case fatality ratio, suggesting the presence of underlying age-specific risk factor(s) of influenza death among young adults.The data (iii) were analyzed by employing the age-period-cohort model, revealing harvesting effect in the period function of TB mortality shortly after the 1918-19 pandemic.

View Article: PubMed Central - PubMed

Affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, 358GA Utrecht, The Netherlands.

ABSTRACT
The epidemiological mechanisms behind the W-shaped age-specific influenza mortality during the Spanish influenza (H1N1) pandemic 1918-19 have yet to be fully clarified. The present study aimed to develop a formal hypothesis: tuberculosis (TB) was associated with the W-shaped influenza mortality from 1918-19. Three pieces of epidemiological information were assessed: (i) the epidemic records containing the age-specific numbers of cases and deaths of influenza from 1918-19, (ii) an outbreak record of influenza in a Swiss TB sanatorium during the pandemic, and (iii) the age-dependent TB mortality over time in the early 20th century. Analyzing the data (i), we found that the W-shaped pattern was not only seen in mortality but also in the age-specific case fatality ratio, suggesting the presence of underlying age-specific risk factor(s) of influenza death among young adults. From the data (ii), TB was shown to be associated with influenza death (P = 0.09), and there was no influenza death among non-TB controls. The data (iii) were analyzed by employing the age-period-cohort model, revealing harvesting effect in the period function of TB mortality shortly after the 1918-19 pandemic. These findings suggest that it is worthwhile to further explore the role of TB in characterizing the age-specific risk of influenza death.

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Related in: MedlinePlus

Tuberculosis mortality from 1900–1940, analyzed by age-period-cohort (APC) model in the USA, Japan, and the Netherlands. (a), (d), and (g) show the age effect, respectively, in the USA, Japan, and the Netherlands. (b), (e), and (h) show the period effect, and (c), (f), and (i) show the cohort effect for the three countries. The precisions of the age grouping were every 10 years for USA and the Netherlands, and every 5 years for Japan. The vertical solid lines and the dotted lines in (b), (e), and (h) represent the year 1918 and the 95% confidence interval (CI) of period effect derived from the profile likelihood. The dashed horizontal lines in all panels mark out the relative risk of 1.
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fig3: Tuberculosis mortality from 1900–1940, analyzed by age-period-cohort (APC) model in the USA, Japan, and the Netherlands. (a), (d), and (g) show the age effect, respectively, in the USA, Japan, and the Netherlands. (b), (e), and (h) show the period effect, and (c), (f), and (i) show the cohort effect for the three countries. The precisions of the age grouping were every 10 years for USA and the Netherlands, and every 5 years for Japan. The vertical solid lines and the dotted lines in (b), (e), and (h) represent the year 1918 and the 95% confidence interval (CI) of period effect derived from the profile likelihood. The dashed horizontal lines in all panels mark out the relative risk of 1.

Mentions: Table 2 compares the goodness of fit of different models in describing observed TB mortality. For all the datasets, the APC model yielded the smallest AIC values for describing the TB mortality (AIC = 2735, 6081, and 1465 for the total populations of the USA, Japan, and the Netherlands, resp.). Figure 3 shows the relative risk estimates from the APC model. The high age-effect was seen among those aged 15–25 years in all three countries, although there was also another hump among the elderly in the USA. As for the period effect, there was a consistent spike in the period effect of TB mortality for all three countries during the Spanish influenza pandemic. More importantly, the spike was followed immediately by significantly steeper decline than before the pandemic. Such tendency of period effect, which could imply that TB mortality was “washed out” by the influenza pandemic, was particularly evident in Japan and the Netherlands, but was less visible in the USA. Nevertheless, we imposed a constraint as shown in (2), and the change in the second derivative was consistently seen in three countries; so the observed patterns of period effect were consistent across countries. Cohort effect did not yield any clear consistent patterns across countries.


The relationship between tuberculosis and influenza death during the influenza (H1N1) pandemic from 1918-19.

Oei W, Nishiura H - Comput Math Methods Med (2012)

Tuberculosis mortality from 1900–1940, analyzed by age-period-cohort (APC) model in the USA, Japan, and the Netherlands. (a), (d), and (g) show the age effect, respectively, in the USA, Japan, and the Netherlands. (b), (e), and (h) show the period effect, and (c), (f), and (i) show the cohort effect for the three countries. The precisions of the age grouping were every 10 years for USA and the Netherlands, and every 5 years for Japan. The vertical solid lines and the dotted lines in (b), (e), and (h) represent the year 1918 and the 95% confidence interval (CI) of period effect derived from the profile likelihood. The dashed horizontal lines in all panels mark out the relative risk of 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3405656&req=5

fig3: Tuberculosis mortality from 1900–1940, analyzed by age-period-cohort (APC) model in the USA, Japan, and the Netherlands. (a), (d), and (g) show the age effect, respectively, in the USA, Japan, and the Netherlands. (b), (e), and (h) show the period effect, and (c), (f), and (i) show the cohort effect for the three countries. The precisions of the age grouping were every 10 years for USA and the Netherlands, and every 5 years for Japan. The vertical solid lines and the dotted lines in (b), (e), and (h) represent the year 1918 and the 95% confidence interval (CI) of period effect derived from the profile likelihood. The dashed horizontal lines in all panels mark out the relative risk of 1.
Mentions: Table 2 compares the goodness of fit of different models in describing observed TB mortality. For all the datasets, the APC model yielded the smallest AIC values for describing the TB mortality (AIC = 2735, 6081, and 1465 for the total populations of the USA, Japan, and the Netherlands, resp.). Figure 3 shows the relative risk estimates from the APC model. The high age-effect was seen among those aged 15–25 years in all three countries, although there was also another hump among the elderly in the USA. As for the period effect, there was a consistent spike in the period effect of TB mortality for all three countries during the Spanish influenza pandemic. More importantly, the spike was followed immediately by significantly steeper decline than before the pandemic. Such tendency of period effect, which could imply that TB mortality was “washed out” by the influenza pandemic, was particularly evident in Japan and the Netherlands, but was less visible in the USA. Nevertheless, we imposed a constraint as shown in (2), and the change in the second derivative was consistently seen in three countries; so the observed patterns of period effect were consistent across countries. Cohort effect did not yield any clear consistent patterns across countries.

Bottom Line: The present study aimed to develop a formal hypothesis: tuberculosis (TB) was associated with the W-shaped influenza mortality from 1918-19.Analyzing the data (i), we found that the W-shaped pattern was not only seen in mortality but also in the age-specific case fatality ratio, suggesting the presence of underlying age-specific risk factor(s) of influenza death among young adults.The data (iii) were analyzed by employing the age-period-cohort model, revealing harvesting effect in the period function of TB mortality shortly after the 1918-19 pandemic.

View Article: PubMed Central - PubMed

Affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, 358GA Utrecht, The Netherlands.

ABSTRACT
The epidemiological mechanisms behind the W-shaped age-specific influenza mortality during the Spanish influenza (H1N1) pandemic 1918-19 have yet to be fully clarified. The present study aimed to develop a formal hypothesis: tuberculosis (TB) was associated with the W-shaped influenza mortality from 1918-19. Three pieces of epidemiological information were assessed: (i) the epidemic records containing the age-specific numbers of cases and deaths of influenza from 1918-19, (ii) an outbreak record of influenza in a Swiss TB sanatorium during the pandemic, and (iii) the age-dependent TB mortality over time in the early 20th century. Analyzing the data (i), we found that the W-shaped pattern was not only seen in mortality but also in the age-specific case fatality ratio, suggesting the presence of underlying age-specific risk factor(s) of influenza death among young adults. From the data (ii), TB was shown to be associated with influenza death (P = 0.09), and there was no influenza death among non-TB controls. The data (iii) were analyzed by employing the age-period-cohort model, revealing harvesting effect in the period function of TB mortality shortly after the 1918-19 pandemic. These findings suggest that it is worthwhile to further explore the role of TB in characterizing the age-specific risk of influenza death.

Show MeSH
Related in: MedlinePlus