Letters

Community acquired pneumonia in elderly people

Addition of erythromycin is not currently justified

This pneumonia is only a small fraction of all hospital cases of chest infection and pneumonia

Authors' reply

Addition of erythromycin is not currently justified

EDITORI agree with Wort and Rogers that current British guidelines on community acquired pneumonia need revision, but I do not believe that the addition of erythromycin should always be considered in elderly people.¹

They cite, as the basis for this recommendation, a study from Israel in which serological evidence of Chlamydia pneumoniae was found in 26% of cases of community acquired pneumonia in elderly people.² It is not clear, in this or other similar studies, whether serological detection of C pneumoniae indicates the cause of the pneumonia or whether treatment directed against it will make a clinical difference. More than one pathogen was identified in 30.4% (age 65-74) and 37.8% (age 75) of cases, but further details are not given. In the original publication other pathogens were also identified in the majority (69%) of cases in which C pneumoniae was found (Streptococcus pneumoniae in 55%).³

A high frequency of copathogens has been found in similar studies, suggesting that C pneumoniae may simply initiate events while the other pathogen causes the pneumonia. Treatment with antibiotics to which C pneumoniae is not sensitive leads to clinical recovery as quickly as when agents to which it is sensitive are given,⁴ supporting this viewpoint. A recent North American study, which included elderly patients, argued that there is no place for routine use of macrolides since only 7.5% of patients were found to have an organism that merited macrolide treatment and none of these patients died.⁵ Other pathogens for which a macrolide is first line treatment have been uncommon in other studies of community acquired pneumonia in elderly people. Disadvantages of concurrent macrolide treatment might include gastrointestinal and other side effects, drug interactions (for example, with theophylline), cost, and the development of macrolide resistancealready, in the United Kingdom, higher in the pneumococcus than for penicillins at 8.6% of isolates.

What is currently lacking most of all is evidence of the frequency of C pneumoniae as a cause of community acquired pneumonia requiring specific treatment. No reliable data exist on the frequency of C pneumoniae in the United Kingdom. Before recommending a macrolide in elderly people with community acquired pneumonia I would like to see a randomised controlled trial of  lactam alone versus  lactam plus macrolide. Until such data are available I suggest that macrolides should be used initially only in severely ill people (in combination with a  lactam), especially when legionella infection is suspected.

Mark Woodhead, Consultant in general and respiratory medicine. ^* .
Department of Respiratory Medicine, Manchester Royal Infirmary, Manchester M13 9WL

^* The author has acted as an adviser to many of the pharmaceutical manufacturers of antibiotics used in the treatment of community acquired pneumonia, including GlaxoWellcome, SmithKline Beecham, Abbott, Hoechst Marion Roussel, Rhone Poulenc, and Bayer.

1. Wort SJ, Rogers TR. Community-acquired pneumonia in elderly people. BMJ 1998; 316: 1690[Free Full Text]. (6 June.)
2. Lieberman D, Schlaeffer F, Porath A. Community-acquired pneumonia in old age: a prospective study of 91 patients admitted from home. Age Ageing 1997; 26: 69-75[Abstract/Free Full Text].
3. Lieberman D, Schlaeffer F, Boldur I, Lieberman D, Horowitz S, Friedman MG, et al. Multiple pathogens in adult patients admitted with community-acquired pneumonia: a one year prospective study of 346 consecutive patients. Thorax 1996; 51: 179-184[Abstract].
4. Kauppinen MT, Saikku P, Kujala P, Herva E, Syrjala H. Clinical picture of community-acquired Chlamydia pneumoniae pneumonia requiring hospital treatment: a comparison between chlamydial and pneumococcal pneumonia. Thorax 1996; 51: 185-189[Abstract].
5. Mundy LM, Oldach D, Auwaerter PG, Gaydos CA, Moore RD, Bartlett JG, et al. Implications for macrolide treatment in community-acquired pneumonia. Chest 1998; 113: 1201-1206[Abstract/Free Full Text].

This pneumonia is only a small fraction of all hospital cases of chest infection and pneumonia

EDITORContrary to the editorial by Wort and Rogers,¹ community acquired pneumonia is not the most common cause of acute hospital admission in any age group, including elderly people. In addition, their statement that 50 000 cases occur each year in the United Kingdom is also misquoted and inaccurate. The study they refer to says, "Around 50 000 people in the UK are admitted to hospital with pneumonia, making it one of the commonest causes of admission."² These data come from NHS hospital statistics, which use the diagnostic code of the international classification of diseases (ICD9-CM), which unfortunately does not specify whether pneumonia is community acquired. As a result, hospital administrative data, even if they are taken at face value, are of limited use to find out different types of pneumonia.³

Community acquired pneumonia has been defined in several ways. If the definition of the British Thoracic Society is used (an acute illness acquired in the community with a new (at least segmental) shadowing in the chest radiograph, and of no known cause or not an expected terminal event) such pneumonia is not the commonest category of chest infection admitted. In fact, a prospective study of community acquired pneumonia in 25 British hospitals over 13.5 months (1982-3) found only 511 adults (of these, 26 did not have pneumonia; age range was 15-74, with four patients outside this range being included).⁴ This gives an average enrolment rate per hospital per month of 1.4. Although this rate may seem widely different from the less controlled hospital data on pneumonia, most doctors familiar with acute hospital medicine would accept it as about right for a small to medium sized district general hospital.

In elderly people (65 years old) the three commonest reasons for acute hospital admission are chest infection, falls, and inability to cope (including due to confusion). Most chest infection in elderly people is due to acute exacerbation of chronic obstructive lung disease, upper respiratory tract infection, non-pneumonic lower respiratory tract infection (bronchitic illness), and aspiration pneumonia. Only a small fraction of all chest infection and pneumonia (including nosocomial pneumonia) in hospital practice is community acquired pneumonia.

M Mamun, Senior registrar. 
University Hospital Aintree, Liverpool L9 7AL

1. Wort SJ, Rogers TR. Community-acquired pneumonia in elderly people. BMJ 1998; 316: 1690. (6 June.)
2. British Thoracic Society. Guidelines for the management of community acquired pneumonia in adults admitted to hospital. Br J Hosp Med 1993; 49: 346-350[Medline].
3. Whittle J, Fine MJ, Joyce DJ, Lave JR, Young WW, Hough LJ, et al. Community acquired pneumonia: can it be defined with claims data? Am J Med Quality 1997; 12: 187-193.
4. British Thoracic Society. Community acquired pneumonia in adults in British hospitals in 1982-83: a survey of aetiology, mortality, prognostic factors, and outcome. Q J Med 1987; 62: 195-220[Abstract/Free Full Text].

Authors' reply

EDITORWe agree with Woodhead that the role of Chlamydia pneumoniae as an aetiological agent in community acquired pneumonia has to be more firmly established, especially in the United Kingdom, where the data on incidence are inadequate. However, in his recent review of guidelines on community acquired pneumonia from 10 European countries, C pneumoniae was described as a causative pathogen in 12% of cases in adults, making it the second most common agent after Streptococcus pneumoniae.¹ In combination with other atypical agents such as Mycoplasma pneumoniae and Legionella spp, such organisms accounted for over 25% of cases of community acquired pneumonia. This is in discordance with the North American study cited by Woodhead, in which atypical agents accounted for only 7.5% of cases.² Conclusions about treatment and outcome from this study must therefore be interpreted with caution. C pneumoniae often seems to be a copathogen and is found in particular with S pneumoniae.³ The synergistic effect may be due to the ciliostatic effect of C pneumoniae rendering the host more susceptible to the second agent. Patients infected with both S pneumoniae and C pneumoniae have a more severe illness.⁴ Therefore C pneumoniae seems not to just initiate events. In patients infected with both organisms treatment with agents that cover only S pneumoniae results in a significantly longer hospital stay than that for patients infected with S pneumoniae alone who are thus treated appropriately.⁴ Clearly further studies are needed to discover the exact role of C pneumoniae in community acquired pneumonia, especially in elderly people who may have more severe disease. However, evidence suggests that it is important as a causative agent and that specific treatment with, for example, a macrolide is appropriate.

Mamun is correct to question our interpretation of the definition of community acquired pneumonia from the study by the British Thoracic Society. However, we suggest that a more accurate representation of the importance of pneumonia may be found in the large study performed by the Unit of Health-Care Epidemiology in Oxford.⁵ In the four age groups studied (15-44, 45-64, 65-74, 75) between 1968 and 1986 only pneumonia and diabetes appeared in the top 10 most common conditions in every group. Pneumonia was the third most common condition in those aged 75 and more common than chronic obstructive lung disease and other respiratory tract infections.

T Rogers, Professor. 
Department of Infectious Diseases, Imperial College School of Medicine, Hammersmith Hospital, London W12 0NN

S J Wort, Specialist registrar in respiratory and transplant medicine. 
Department of Transplant Medicine, Royal Brompton and Harefield NHS Trust, Harefield Hospital, Middlesex UB9 6JH

1. Woodhead M. Community-acquired pneumonia guidelinesan international comparison. Chest 1998; 113: 183-17S.
2. Mundy LM, Oldach D, Auwaerter PG, Gaydos CA, Moore RD, Bartlett JG, et al. Implications for macrolide treatment in community-acquired pneumonia. Chest 1998; 113: 1201-1206.
3. Lieberman D, Schlaeffer F, Boldur I, Lieberman D, Horowitz S, Friedman MG, et al. Multiple pathogens in adult patients admitted with community-acquired pneumonia: a one year prospective study of 346 consecutive patients. Thorax 1996; 51: 179-184.
4. Kauppinen MT, Saikku P, Kujala P, Herva E, Syrjala H. Clinical picture of community-acquired Chlamydia pneumoniae pneumonia requiring hospital treatment: a comparison between chlamydial and pneumococcal pneumonia. Thorax 1996; 51: 185-189.
5. Ashton CM, Ferguson JA, Goldacre MJ. In-patient workload in medical specialities. II. Profiles of individual diagnoses from linked statistics. Q J Med 1995; 88: 661-672.