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Comparison of different pain scoring systems in critically ill patients in a general ICU

Sabine JGM Ahlers123*, Laura van Gulik1, Aletta M van der Veen1, Hendricus PA van Dongen1, Peter Bruins1, Svetlana V Belitser4, Anthonius de Boer4, Dick Tibboel3 and Catherijne AJ Knibbe23

Author Affiliations

1 Department of Anaesthesiology and Intensive Care, St. Antonius Hospital, Koekoekslaan 1, Nieuwegein, 3440 EM, The Netherlands

2 Department of Clinical Pharmacy, St. Antonius Hospital, Koekoekslaan 1, Nieuwegein, 3440 EM, The Netherlands

3 Department of Pediatric Surgery, Erasmus Medical Centre, Sophia Children's Hospital, Dr. Molewaterplein 60, Rotterdam, 3015 GJ, The Netherlands

4 Department of Pharmacoepidemiology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Utrecht, Sorbonnelaan 16, Utrecht, 3584 CA, The Netherlands

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Critical Care 2008, 12:R15  doi:10.1186/cc6789

See related commentary by Skrobik,

Published: 16 February 2008



Pain in critically ill patients in the intensive care unit (ICU) is common. However, pain assessment in critically ill patients often is complicated because these patients are unable to communicate effectively. Therefore, we designed a study (a) to determine the inter-rater reliability of the Numerical Rating Scale (NRS) and the Behavioral Pain Scale (BPS), (b) to compare pain scores of different observers and the patient, and (c) to compare NRS, BPS, and the Visual Analog Scale (VAS) for measuring pain in patients in the ICU.


We performed a prospective observational study in 113 non-paralyzed critically ill patients. The attending nurses, two researchers, and the patient (when possible) obtained 371 independent observation series of NRS, BPS, and VAS. Data analyses were performed on the sample size of patients (n = 113).


Inter-rater reliability of the NRS and BPS proved to be adequate (kappa = 0.71 and 0.67, respectively). The level of agreement within one scale point between NRS rated by the patient and NRS scored by attending nurses was 73%. However, high patient scores (NRS ≥4) were underestimated by nurses (patients 33% versus nurses 18%). In responsive patients, a high correlation between NRS and VAS was found (rs = 0.84, P < 0.001). In ventilated patients, a moderate positive correlation was found between the NRS and the BPS (rs = 0.55, P < 0.001). However, whereas 6% of the observations were NRS of greater than or equal to 4, BPS scores were all very low (median 3.0, range 3.0 to 5.0).


The different scales show a high reliability, but observer-based evaluation often underestimates the pain, particularly in the case of high NRS values (≥4) rated by the patient. Therefore, whenever this is possible, ICU patients should rate their pain. In unresponsive patients, primarily the attending nurse involved in daily care should score the patient's pain. In ventilated patients, the BPS should be used only in conjunction with the NRS nurse to measure pain levels in the absence of painful stimuli.