Family Practice Advance Access originally published online on June 29, 2007
Family Practice 2007 24(4):317-322; doi:10.1093/fampra/cmm023
Is co-morbidity taken into account in the antibiotic management of elderly patients with acute bronchitis and COPD exacerbations?
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, The Netherlands
Correspondence to: J. Bont, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, PO Box 85060, 3508 AB Utrecht, The Netherlands. Email: j.bont{at}umcutrecht.nl
Received 6 November 2006; Revised 23 March 2007; Accepted 25 April 2007.
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Abstract |
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Background. Guidelines on acute lower respiratory tract infections recommend restrictive use of antibiotics, however, in patients with relevant co-morbid conditions treatment with antibiotics should be considered. Presently, it is unknown whether GPs adhere to these guidelines and target antibiotic treatment more often at patients with risk-elevating conditions.
Objectives. We assessed whether in elderly primary care patients with acute bronchitis or exacerbations of chronic pulmonary disease (COPD), antibiotics are more often prescribed to patients with risk-elevating co-morbid conditions.
Methods. Using the Utrecht GP research database, we analysed 2643 episodes in patients of 65 years of age or older with a GP-diagnosed acute bronchitis or exacerbation of COPD. Multivariable logistic regression analysis was applied to determine independent determinants of antibiotic use.
Results. Antibiotic prescribing rates were high in both acute bronchitis (84%) and in exacerbations of COPD (53%). In acute bronchitis, only age was an independent determinant of antibiotic use [odds ratio (OR) 1.03, 95% confidence interval (CI) 1.003–1.048], whereas in exacerbations of COPD antibiotics were more often prescribed to male patients (OR 1.3, 95% CI 1.0–1.5), patients with diabetes (OR 1.7, 95% CI 1.1–2.4) and heart failure (OR 1.3, 95% CI 1.0–1.7).
Conclusion. Dutch GPs prescribe antibiotics in the majority of elderly patients with acute bronchitis and in half of the episodes of exacerbations of COPD. Tailoring their antibiotic treatment according to the presence or absence of high-risk co-morbid conditions could help GPs in improving antibiotic use in patients with respiratory tract infections in primary care.
Keywords. Aged, antibiotic treatment, co-morbidity, primary health care, respiratory tract infections.
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Introduction |
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Acute lower respiratory tract infections (LRTIs) are a major cause of morbidity and mortality, and one of the most frequent reasons to seek primary medical care.1,2 Indications for antimicrobial treatment in patients with LRTI are still debated. Only in patients with a pneumonia diagnosis, studies demonstrated that antibiotics favorably influence prognosis.3 The effectiveness of antibiotic treatment in acute bronchitis or exacerbations of chronic pulmonary disease (COPD), however, remains controversial.4–10 In the absence of a sound evidence base, American11 European12 and national guidelines13 on LRTI recommend antibiotics for patients with suspected pneumonia and in patients with acute bronchitis with certain chronic conditions and thus to withhold antibiotics from relatively healthy patients.
Presently, it is unknown whether GPs adhere to these guidelines and target antibiotic treatment more often at patients with risk-elevating conditions. The Utrecht Medical Center GP research database enabled us to address this issue.
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Methods |
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Design and setting
In this retrospective cohort study, we included data from community-dwelling elderly patients with episodes of LRTI, diagnosed in Dutch primary care. The general practices involved were part of the Utrecht GP Research Network. Currently, 35 GPs from this network serve approximately 58 000 non-institutionalized persons. Participating GPs keep a uniform, structured registration of medical data, using computerized medical records (ELIAS, Isoft, Nieuwegein). The network has been described in detail elsewhere.14 Diagnosis and drug prescriptions are registered using the International Classification of Primary Care (ICPC)15 and Anatomical Therapeutically Classification codes,16 respectively. All data are stored in a computerized central database.
Study population
From January 1997 until October 2003, all patients aged 65 years and older, with a GP-diagnosed acute bronchitis or exacerbations of COPD were included. A diagnosis of acute bronchitis was made when patients met the ICPC criteria for acute bronchitis (R78), consisting of coughing and fever with diffuse abnormalities on pulmonary examination like wheezing and crepitations.17 Since fever is often absent in elderly, we allowed for this criterion to be ignored. When an episode of acute bronchitis was diagnosed and the patient had a history of COPD, the episode was recoded into an exacerbation of COPD. Since ICPC coding is absent for exacerbations of COPD, we accepted the diagnosis of the GP. We defined exacerbations of COPD according to the Anthonisen criteria in the absence of a GP diagnosis.4 Criteria were met if two out of three symptoms (increased dyspnoea, sputum volume and sputum purulence) were present in patients with known COPD. When only one of these symptoms occurred, at least one other finding (signs of upper respiratory tract infection such as sore throat and nasal discharge within the past 5 days, fever without other cause, increased wheezing, increased cough or increase in either respiratory rate or heart rate) had to be present. During the study period, patients could provide more than one episode of LRTI. Patients in secondary or tertiary care at the time of diagnosis, with a diagnosis of lung cancer, human immunodeficiency virus or hematological malignancies, or those who used immunosuppressive medication other than oral glucocorticoids were not included.
Selection of risk factors for a complicated course
For the selection of possible determinants from medical history, we included relevant items, such as age, a history of heart failure, severe COPD or neurological disorders, mentioned in the Dutch guideline on acute cough13 as well as potential risk-elevating co-morbid conditions from available prognostic studies not mentioned in the guideline.18–23 Co-morbidity was defined as the presence of a co-morbid condition in the patient's history recorded according to the ICPC coding system. The following relevant variables were included: increasing age, male gender, presence of COPD or, emphysema (R91, R95) or asthma (R96), diabetes mellitus (T90), presence of a malignancy, congestive heart failure (K77, K82), cardiovascular diseases [defined as angina pectoris (K74) or myocardial infarction (K75, K76)], stroke (K90), dementia (P70), renal disease (U99) and current use of antibiotics. Severe COPD was indicated by the presence of maintenance therapy with oral glucocorticoids, since severe COPD is not always accurately recorded in medical files. Similarly, the presence of diabetes was indicated by the use of oral diabetic medication or insulin.
Data collection and data analysis
All variables, except for age, were classified as dichotomous variables. Descriptive statistics as proportions, means and ORs were calculated using SPSS for Windows (version 12.0.1) in order to define our study population in terms of baseline characteristics.
To assess the associations between antibiotic use and risk-related variables, we excluded all episodes in which the patient was immediately admitted to hospital (n = 63), as treatment is often postponed until arrival in hospital. We applied univariable logistic regression to obtain estimates of associations between prescriptions of antibiotics and the presence of potential risk factors for complications given by odds ratios (ORs) and their corresponding 95% confidence intervals (CIs). Variables with a P level of 0.15 or lower were further examined in the multivariable logistic regression analysis, and a P level of 0.05 was considered to indicate statistical significance. The analysis was repeated including only first episodes for each person to control for within-person dependency.
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Results |
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From January 1997 until October 2003, 2643 episodes of LRTI were recorded in 1693 patients, with an average of 1.9 episodes per patient. We recorded 1120 episodes of acute bronchitis and 1523 exacerbations of COPD in 1362 patients. In all, 542 patients were included more than once; 456 exacerbations of COPD were primarily diagnosed as acute bronchitis and were recoded into exacerbations of COPD due to the presence of COPD in the medical history. The populations' mean age was 75 years (SD 7 years). Co-morbid conditions were common in this population (86%), mostly COPD, emphysema or asthma (47% of episodes) and heart failure was present in 21% and angina pectoris in 17%. In all, 175 (6.6%) patients were hospitalized or died within 30 days after the diagnosis was made (Table 1).
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The majority of episodes of LRTI were handled in primary care and 2.4% of cases were referred to hospital within 2 days after first presentation at the GP practice (Table 2). Admission rates were lower for episodes of acute bronchitis (0.4%) than in patients with exacerbations of COPD (4%). In episodes of patients not directly admitted to hospital, GPs prescribed medication in the majority of cases. Acute bronchitis was treated with antibiotics in 84% of cases. Exacerbations of COPD were treated primarily with lung medication (75% of cases), while antibiotics were given in 53% of episodes.
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In patients with an acute bronchitis, we found a weak but significant association between antibiotic prescription and age only (OR 1.03, 95% CI 1.003–1.048) (Table 3). In patients with exacerbations of COPD, antibiotics were more readily prescribed to male patients (OR 1.3, 95% CI 1.0–1.5). Furthermore, GPs prescribed antibiotics more often in patients with exacerbations of COPD when also diabetes was present (OR 1.7, 95% CI 1.1–2.4) and when there was a history of heart failure (OR 1.3, 95% CI 1.0–1.7). No significant association was observed with other co-morbid conditions (Table 4). These co-morbid conditions were independent determinants for antibiotic prescriptions, except for a history of a myocardial infarction. Controlling for within-person dependency by reanalysing our data taking only the first episodes into account gave similar estimations of associations between determinants and outcome.
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Discussion |
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Key findings
This study showed that GPs prescribe antibiotics in the majority of cases of acute bronchitis and exacerbations of COPD. In case of acute bronchitis, we found no association between co-morbid conditions and antibiotic use, whereas in exacerbations of COPD antibiotics were more often prescribed to patients with diabetes mellitus and heart failure.
Limitations
Some limitations of our study should be mentioned. We missed valid information on history taking and physical examination, as well as information on smoking behaviour. Clinical information could give more insight in prescribing behaviour of GPs. For instance, previous studies have shown an association between clinical parameters, e.g. fever, with antibiotic use.24,25 On the other hand, other studies have shown no relation between antibiotics and clinical parameters.7,26 Apart from signs and symptoms we, however, think that co-morbid conditions should be taken into account when deciding on antibiotic treatment, because we saw in a recent study that co-morbidity predicts poor outcome.27 Prospective studies should, however, be done to elucidate the effects of antibiotics in patients with different clinical syndromes and different chronic conditions and further improve and specify current guidelines on antibiotic therapy.
Also, the database did not allow us to collect information on the severity of co-morbid conditions, possibly leading to an underestimation of associations. For example, patients with severe heart failure or renal disease may have received antibiotics more often, whereas we could not demonstrate this. In spite of the retrospective design, this study ensured that participating GPs made their decisions concerning treatment and referral independently and shows the presence or absence of relations of prescription of antibiotics with easy obtainable information on co-morbid conditions of the patients. Consequently, the results of this study describe the customary course of events of LRTI in primary care. We have described setting and patients as detailed as possible and international criteria were used to categorize diagnoses and medical treatment. Therefore, we think that our results are also of importance for similar primary settings in other countries.
External comparison
The prescription rate of antibiotics in episodes of acute bronchitis found in this study is high. Nevertheless, it is largely in accordance with many other studies.24,26,28 Some studies show somewhat lower prescription rates in acute bronchitis.7,9,29 We assume that the high prescription rate is caused by the high age of our study population. Secondly, it is often difficult to differentiate between acute bronchitis and pneumonia in the absence of a pulmonary X-ray and therefore antibiotics are often prescribed.
In exacerbations of COPD, our prescription rates were higher compared to other studies.29–31 The main reason for these discrepancies might be again the inclusion of older patients in our study. Only one study had higher rates of antibiotic prescriptions probably because of the hospital setting.32
Importantly, our data show that the indications that GPs use in daily practice do not concur with indications mentioned in evidence-based guidelines as far as it concerns the presence of co-morbid conditions. So far, we are aware of only few studies focusing specifically on the association between prescribing antibiotics and the presence of potential risk factors in case of acute bronchitis or exacerbations of COPD.7,9,24,26,28,33 In contrast to our study, two of these studies did not find high age being a predictive characteristic for prescribing antibiotics. Also gender has not been related to antibiotic management in previous studies and these studies included few elderly.28,33
In general, antibiotics are less often prescribed in Dutch primary care compared to other countries.34 This is most likely explained by strong recommendations in Dutch guidelines to withhold from antibiotics unless the effect is proven. Nevertheless, our study and a previous study from Akkerman et al.24 show higher antibiotic prescription rates than expected according to guidelines. According to literature and these guidelines, we expected that prescriptions rates were higher in patients with risk-related co-morbidity and less in patients without co-morbidity. Our results do not support this reasoning. Also, after taking the number of co-morbid conditions into account, we could not find a significant association between co-morbid conditions and antibiotic prescribing (data not shown).
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Conclusion |
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Until definite results from future preferably randomized controlled trials on this subject are available, GPs should be urged to more use information, in addition to other considerations, about the presence or absence of risk-related co-morbid conditions in their decision to prescribe antibiotics to patients with acute bronchitis or exacerbations of COPD. Tailoring their antibiotic treatment in this way could help GPs to improve antibiotic use in patients with respiratory tract infections in primary care.
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Declaration |
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Funding: Netherlands Scientific Organisation (AGIKO No. 920-03-254) to JB. The research database of the University Medical Center Utrecht primary care network is funded by the UMC Utrecht.
Ethical approval: None.
Conflicts of interest: All authors declare that there are no conflicts of interest.
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Notes |
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Bont J, Hak E, Birkhoff CE, Hoes AW, Verheij TJM. Is co-morbidity taken into account in the antibiotic management of elderly patients with acute bronchitis and COPD exacerbations? Family Practice 2007; 24: 317–322.
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