Clinical and economic burden of community-acquired pneumonia amongst adults in the Asia-Pacific region

Abstract

Community-acquired pneumonia (CAP) is an important cause of mortality and morbidity amongst adults in the Asia-Pacific region. Literature published between 1990 and May 2010 on the clinical and economic burden of CAP amongst adults in this region was reviewed. CAP is a significant health burden with significant economic impact in this region. Chronic obstructive pulmonary disease, cardiovascular disease, diabetes mellitus and advanced age were risk factors for CAP. Aetiological agents included Streptococcus pneumoniae, Klebsiella pneumoniae, Gram-negative bacteria, Mycobacterium tuberculosis, Burkholderia pseudomallei, Staphylococcus aureus and atypical pathogens (Mycoplasma pneumoniae, Chlamydophila pneumoniae and Legionella spp.), with important differences in the prevalence of these pathogens within the region. Antibiotic resistance was significant but was not linked to excess mortality. Aetiological pathogens remained susceptible to newer antimicrobial agents. Rational antibiotic use is essential for preventing resistance, and increased surveillance is required to identify future trends in incidence and aetiology and to drive treatment and prevention strategies.

Introduction

Community-acquired pneumonia (CAP) is an important cause of morbidity and mortality worldwide. Lower respiratory tract infections (LRTIs), including CAP, ranked third amongst the 20 leading causes of death by the World Health Organization (WHO), causing an estimated 429.2 million episodes of illness worldwide in 2004 [1]. LRTIs were also the leading cause of burden of disease measured in terms of disability-adjusted life years (DALYs) (defined by WHO as one lost year of ‘healthy’ life, and the burden of disease as a measurement of the gap between current health status and an ideal situation where everyone lives into old age, free of disease and disability) amongst all age groups worldwide, accounting for 94.5 million DALYs in 2004 [1].

The risk of respiratory infections increases with age [2], [3], [4]. The incidence of CAP was six-fold higher in adults in Finland aged ≥75 years compared with adults aged 30–44 years [5]. In rural Thailand, the incidence of CAP increased after 55 years of age [6]. Two studies documented the increased long-term (>1 year) mortality risk amongst elderly adults treated for CAP in ambulatory and hospital settings [7], [8]. The long-term risk of pneumonia-related mortality was three-fold higher in patients recovering from pneumococcal pneumonia and conferred a relative risk of 1.5 for all-cause mortality [7]. The percentage of adults aged ≥60 years in the population is expected to double between 2010 and 2050 worldwide, underscoring the importance of preventing CAP in the elderly [9].

The burden of CAP amongst adults in the Asia-Pacific region may be underestimated owing to self-treatment with antibiotics where they are available over the counter [10], [11], poor accessibility to and high costs of diagnostic testing [12], lack of surveillance programmes (especially in rural areas), and the practice of treating empirically versus obtaining a definitive diagnosis [13], [14], [15]. Practical difficulties (lack of a productive cough and administering antibiotics before obtaining cultures) may leave the aetiological pathogen unidentified [11], [16], [17]. Limitations on the sensitivity of diagnostic tests may also contribute to this problem. Reliable data are available primarily for patients receiving hospital-based care. Since a substantial proportion of patients with CAP are treated as outpatients, estimates of disease burden based on studies of hospitalised patients may not capture the complete picture [5], [18]. In addition, factors contributing to the economic burden of CAP in the Asia-Pacific region, such as direct and indirect treatment costs and lost productivity, remain unidentified.

Literature published between 1990 and May 2010 was reviewed to evaluate factors impacting the clinical and economic burden of CAP amongst adults in the Asia-Pacific region.