Incidence of community-acquired lower respiratory tract infections and pneumonia among older adults in the United Kingdom: a population-based study

Abstract

Community-acquired lower respiratory tract infections (LRTI) and pneumonia (CAP) are common causes of morbidity and mortality among those aged ≥65 years; a growing population in many countries. Detailed incidence estimates for these infections among older adults in the United Kingdom (UK) are lacking. We used electronic general practice records from the Clinical Practice Research Data link, linked to Hospital Episode Statistics inpatient data, to estimate incidence of community-acquired LRTI and CAP among UK older adults between April 1997-March 2011, by age, sex, region and deprivation quintile. Levels of antibiotic prescribing were also assessed. LRTI incidence increased with fluctuations over time, was higher in men than women aged ≥70 and increased with age from 92.21 episodes/1000 person-years (65-69 years) to 187.91/1000 (85-89 years). CAP incidence increased more markedly with age, from 2.81 to 21.81 episodes/1000 person-years respectively, and was higher among men. For both infection groups, increases over time were attenuated after age-standardisation, indicating that these rises were largely due to population aging. Rates among those in the most deprived quintile were around 70% higher than the least deprived and were generally higher in the North of England. GP antibiotic prescribing rates were high for LRTI but lower for CAP (mostly due to immediate hospitalisation). This is the first study to provide long-term detailed incidence estimates of community-acquired LRTI and CAP in UK older individuals, taking person-time at risk into account. The summary incidence commonly presented for the ≥65 age group considerably underestimates LRTI/CAP rates, particularly among older individuals within this group. Our methodology and findings are likely to be highly relevant to health planners and researchers in other countries with aging populations.

Figure 1. Incidence of LRTI and CAP by sex over time.

Crude and age-standardised incidence of a) LRTI and b) CAP by sex over time. Standardised to UK population, mid-year 2004.

Figure 2. Incidence of LRTI and CAP by age and sex over time.

Incidence by age of LRTI in a) men, b) women and CAP in c) men, d) women over time.

Figure 3. Age-standardised incidence of LRTI and CAP by region and sex.

Age-standardised incidence of a) LRTI and b) CAP by region and sex. Standardised to UK population, mid-year 2004.

Figure 4. Age-standardised incidence of LRTI and CAP by IMD quintile and sex.

Age-standardised incidence of a) LRTI and b) CAP by index of multiple deprivation quintile and sex. Standardised to UK population, mid-year 2004.