Is it time to rethink the urea criterion in CURB-65?

Abstract

We read the article by CAPELASTEGUI et al.[1] on the validation of the severity assessment rules for the management of community-acquired pneumonia (CAP) with interest. The authors concluded that CURB-65 (confusion, urea .7 mmol? L -1 , respiratory rate o30?min -1 , low systolic (,90 mmHg) or diastolic (f60 mmHg) blood pressure, and aged o65 yrs) and CRB-65 indices recommended by the British Thoracic Society are indeed useful and easy to apply in day-to-day clinical practice, thereby helping in risk stratification and management as demonstrated by LIM et al. [2].With the current demographic trends, the proportion of the older population is set to rise. Globally, the projected number of people aged o65 yrs will double between 2000 and 2030 [3]. Moreover, CAP is common in older people and is associated with high mortality [4]. We note that the mean ages of patients reported in CAPELASTEGUI et al. [1] and LIM et al.[2] were 64.1 and 61.8 yrs, respectively. In a prospective study of elderly patients aged o65 yrs with CAP (mean¡SD age 81.1¡7.9 yrs), we reported that the sensitivity and specificity of CURB in predicting death were 81 and 52%, respectively [5]. The specificity figure of this elderly cohort was much lower than in other studies of younger patients [2,6,7]. Due to this low specificity, the CURB-65 criteria in their current form are not ideal for assessing older CAP patients.In the same study, we found that the urea criterion was only of borderline significance and cautioned that the urea cut-off point of .7 mmol?L -1 in the CURB criteria may not be a sufficiently specific parameter [5]. This may be due to the fact that chronic renal impairment is more prevalent in the older population, and dehydration, which is common in acutely unwell older patients, may also contribute to a higher urea level [8]. With this background, we set out to assess whether raising the cut-off point of urea, while keeping the other criteria in CURB-65 as they are, would improve the specificity and positive predictive value (PPV) of the criteria in predicting mortality.Analyses were conducted based on data from two prospective cohort studies [5,7], which were carried out in a single institute in UK using similar inclusion and exclusion criteria. Although all ages were included in the first study [7], in the second study only those who were aged o65 yrs were included [5]. Therefore, the compilation cohort consisted of a higher number of older patients with CAP and a higher mean age (mean¡SD age 70.3¡18.2 yrs) compared with previously reported studies.A total of 193 patients were included in the currently reported analysis. It was hypothesised that increasing the urea cut-off level in older people would improve the specificity of CURB-65. This hypothesis was tested by increasing the urea cutoff point by 2 mmol?L -1 each time from the currently recommended urea cut-off level of .7 mmol?L -1 (i.e. CU9RB-65 with urea cut-off .9 mmol?L -1 , CU11RB-65 using urea cutoff .11 mmol?L -1 and CU13RB-65 using urea cut-off .13 mmol?L -1 ), and th...

Identifying severe community‐acquired pneumonia in the emergency department: A simple clinical prediction tool

“…When classifying patients into high‐ and low‐risk groups, the new tool had the advantage of including a smaller proportion of the total number of patients presenting to the ED than CRB65 (41.4% vs 63.6%). This percentage differed from previous studies of CRB65, because our study did not include the many patients who might be managed by a general practitioner, 15 but instead focused only on patients referred to the hospital. Importantly, this does not imply that all 41.1% would be admitted to ICU, but instead that inexperienced doctors would seek assistance when assessing this patient group, and would evaluate these patients more closely.…”

“…one additional variable). Accuracy must be balanced against simplicity and practicality for use at the point of care 15–18 . Hypoxia is, however, usually easy to measure by pulse oximetry; hence, its inclusion in a tool is probably justified.…”

Performance of CURB-65 and CURB-age in community-acquired pneumonia

“…Currently recommended severity assessment criteria by BTS were based on the CURB-65 developed by Lim et al (6). However, their usefulness in the elderly patients with CAP has been questioned (7,8). We have shown that simple modification of CURB-65 using CURB-age criteria better identified patients who are at high risk of mortality from CAP (9).…”