Elsevier

The Lancet

Volume 390, Issue 10098, 2–8 September 2017, Pages 935-945
The Lancet

Articles
Trends in international asthma mortality: analysis of data from the WHO Mortality Database from 46 countries (1993–2012)

https://doi.org/10.1016/S0140-6736(17)31448-4Get rights and content

Summary

Background

International time trends in asthma mortality have been strongly affected by changes in management and in particular drug treatments. However, little is known about how asthma mortality has changed over the past decade. In this study, we assessed these international trends.

Methods

We collated age-standardised country-specific asthma mortality rates in the 5–34 year age group from the online WHO Mortality Database for 46 countries. To be included in the analysis, we specified that a country must have 10 years of complete data in the WHO Mortality Database between 1993 and 2012. In the absence of consistent and accurate asthma prevalence and prescribing data, we chose to use a locally weighted scatter plot smoother (LOESS) curve, weighted by the individual country population in the 5–34-year age group to show the global trends in asthma mortality rates with time.

Findings

Of the 46 countries included in the analysis of asthma mortality, 36 were high-income countries, and 10 were middle-income countries. The LOESS estimate of the global asthma mortality rate was 0·44 deaths per 100 000 people (90% CI 0·39–0·48) in 1993 and 0·19 deaths per 100 000 people (0·18–0·21) in 2006. Despite apparent further reductions in some countries and regions of the world, there was no appreciable change in global asthma mortality rates from 2006 through to 2012, when the LOESS estimate was also 0·19 deaths per 100 000 people (0·16–0·21).

Interpretation

The trend for reduction in global asthma mortality observed since the late 1980s might have stalled, with no appreciable difference in a smoothed LOESS curve of asthma mortality from 2006 to 2012. Although better implementation of established management strategies that have been shown to reduce mortality risk is needed, to achieve a further substantive reduction in global asthma mortality novel strategies will also be required.

Funding

The Medical Research Institute of New Zealand, which is supported by Health Research Council of New Zealand Independent Research Organisation.

Introduction

Trends in international asthma mortality rates provide a useful barometer of the burden of asthma and the impact of changes in asthma management.1, 2 These trends helped to identify so-called epidemics of asthma mortality in some but not all countries in the 1960s3 and in the 1970s and 1980s.4 These high asthma mortality rates were shown to be due to the overuse of the high-dose, potent, poorly selective β2 agonists isoprenaline forte and fenoterol,5, 6 and the epidemics abruptly ended with the regulatory restriction or withdrawal of these drugs.1, 2, 7 It was recognised that β2 agonists as a drug class had the potential for long-term adverse effects, increasing asthma severity through enhanced bronchial hyperresponsiveness and reduced lung function.8, 9 The potential for acute cardiovascular adverse effects in the context of hypoxaemia in acute severe asthma was also recognised, with these effects greater with the specific β2 agonists that caused asthma mortality epidemics.8, 9, 10 It was also shown that the excessive use of β2 agonists might increase mortality risk through masking of symptoms of deteriorating asthma, potentially leading to a delay in recognising the presence of a severe life-threatening asthma attack.9, 10

Realisation of the potential risks of over-reliance on bronchodilator therapy, and the efficacy of inhaled corticosteroids (ICS) in reducing morbidity and risk of mortality in asthma11 led to a change in practice in the treatment of asthma in the late 1980s. The use of ICS increased in many countries worldwide, more recently in the form of ICS/long-acting β2 agonist (LABA) combination therapy, in which the LABA component essentially represented a vehicle for improved compliance with ICS use.12, 13, 14, 15, 16, 17, 18, 19, 20 This ICS-based management approach was associated with a widespread and progressive reduction in international asthma mortality from 0·62 deaths per 100 000 people per year in 1985–86, to 0·23 deaths per 100 000 people per year in 2004–05, in the 20 countries in which data for the 5–34-year age group were available.21 This finding represented a 63% reduction in international asthma mortality over the 20-year period.

However, the international trends in asthma mortality over the past decade are unknown. The purpose of the analysis published in this report has been to document the trends in asthma mortality in the 10-year period since the last review,21 by use of WHO mortality data in the 46 countries in which data were available. As previously, asthma mortality data were obtained in the 5–34-year age group because of the accuracy of death certification of asthma in this age group and the lower risk of confounding from the diagnosis of chronic obstructive pulmonary disease (COPD) in older age groups.3, 22, 23, 24

Research in context

Evidence before this study

International trends in asthma mortality rates provide useful information about the burden of asthma and the impact of changes in asthma management. In this way, asthma mortality epidemics were identified in some but not all countries in the 1960s, 1970s, and 1980s. These epidemics were shown to be due to the overuse of the high-dose, potent, poorly selective β2 agonists isoprenaline forte and fenoterol, with the epidemics abruptly ending with their regulatory restriction or withdrawal. Since the 1980s there has been a marked increase in the use of inhaled corticosteroids (ICS) in the management of asthma. This change in management has been associated with a progressive two-thirds reduction in the estimated mean global asthma mortality rate between 1985 and 2005. On Oct 5, 2015, we searched MEDLINE with the terms “asthma” and “mortality” for publications in English published since 2009. This search revealed that international trends in asthma mortality over the past decade had not yet been reported.

Added value of this study

International trends in asthma mortality rates in the 5–34-year age group over the past decade are reported and analysed. Our analysis shows that estimated global asthma mortality rates in the 5–34-year age group have not appreciably changed over the past decade. Although in some countries and regions the asthma mortality rate has continued to fall, the estimated global asthma mortality rate has not changed since 2006. With 46 countries represented in our dataset, this is the most comprehensive analysis of international asthma mortality trends to date.

Implications of all the available evidence

The marked and progressive reduction in international asthma mortality rates observed since the late 1980s has plateaued, with no appreciable change in global asthma mortality rates since 2006. Although better implementation of established management strategies that have been shown to reduce mortality risk is needed, novel strategies will be required to achieve a further substantive reduction in global asthma mortality.

Section snippets

Data sources and procedures

The principal data source was the online WHO Mortality Database.25 This database is a compilation of mortality data by age, sex, and cause of death, as reported annually by WHO member states from their civil registration systems. We extracted the crude number of asthma deaths and the corresponding population estimate for the 5–34-year age group, for all available countries and years. To be included in the analysis, we specified that a country must have at least 10 years of complete data in the

Results

Age-standardised mortality rates were available for 46 countries from the online WHO Mortality Database for the years 1993–2012 (table 1). Of the 46 countries included in the analysis, 36 (78%) were high-income countries and 10 (22%) were middle-income countries. For three of these countries—Canada (2006–11), New Zealand (2011–12), and the USA (2008–12)—data from recent years were not available on the WHO Mortality Database, so they were instead extracted online from the national statistics

Discussion

This analysis shows that estimated global asthma mortality rates in the 5–34-year age group have not appreciably changed over the past decade. Although in some countries and regions the asthma mortality rate has continued to decrease, the estimated global asthma mortality rate has not appreciably changed since 2006. This finding suggests that progress made in the previous two decades might have stalled, indicating that better implementation of current management strategies known to reduce

References (41)

  • R Beasley et al.

    International trends in asthma mortality

  • N Pearce et al.

    Epidemiology of asthma mortality

  • FE Speizer et al.

    Observations on recent increase in mortality from asthma

    BMJ

    (1968)
  • RT Jackson et al.

    Mortality from asthma: a new epidemic in New Zealand

    BMJ

    (1982)
  • PD Stolley

    Why the United States was spared an epidemic of deaths due to asthma

    Am Rev Respir Dis

    (1972)
  • R Beasley et al.

    Asthma mortality and inhaled beta agonist therapy

    Aust NZ J Med

    (1991)
  • J Crane et al.

    Asthma and the β agonist debate

    Thorax

    (1995)
  • H Neffen et al.

    Asthma mortality, inhaled steroids, and changing asthma therapy in Argentina (1990–1999)

    Respir Med

    (2000)
  • DL Lim et al.

    Trends in sales of inhaled corticosteroids and asthma outcomes in Singapore

    Thorax

    (2006)
  • CR Kumana et al.

    Increasing use of inhaled steroids associated with declining asthma mortality

    J Asthma

    (2001)
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