How to measure recovery…

Aldrete JA & Kroulik. A postanesthetic recovery score. Anesthesia & Analgesia 1970; 49: 924-934

RHH Journal Club. May 30th, 2013. Dr Iain Goodhart

Full-text article (if available)

This paper describes the process by which the (Post Anaesthetist Recovery Score) PARS score was designed, evaluated and validated. This score is the foundation of many of the currently used patient risk assessment scores.

Study design

This was a multicentre prospective observational study in the USA in late 1960’s


A scoring system (PARS) was designed and then applied to a selection of patients that had undergone a variety of anesthetics in at least three different hospitals in the USA. The score, demographics and type of Anaesthetic were then analysed.

Population: 352 patients (100 from Denver, 152 from Colorado and 100 from other centers) age, and gender are not stated.

Intervention/control: There was no intervention or control.

Primary outcome:  The PARS score on arrival in recovery and at hourly intervals thereafter. The authors sought to illustrate a change in the score during the patients stay in recovery.

Secondary outcomes: Through the analysis of the independent variables the authors attempted to identify independent variables that effected PARS scores.


The paper does not report absolute numbers so it is not possible to make a proper evaluation of groups that were use in the analysis of independent variables. The paper states that the patients were selected at random and validates this statement by describing the variety of practitioners, surgical specialties and anaesthetic techniques. However, the number of patients in the study represents a small proportion of the overall patient throughput in the institutions thus the selection may be more opportunistic than truly random. The study was not blinded, but an attempt was made to assess confounding factors. There is no statement on follow up or complications post discharge. However significant progress has been made in pharmacology and anaesthetic techniques since this study.  There is no statement of ethical approval.


Primary outcome: The study found that the score was capable of showing a change in patient status during the patients stay in recovery and that patients were not discharged until a minimum score was attained.

Secondary outcome: The study reports lower PARS scores with certain muscle relaxants, patients who had had cardiac, thoracic, abdominal and orthopaedic surgery. Increased duration of anaesthesia was also associated with lower PARS scores. However, the numbers involved are probably too small for these differences to be statistically significant.

Take home message: This paper describes the PARS score and the its composite domains, but the statements relating to independent variables that effect PARS scores should be interpreted with caution. The PARS score is probably of limited value since the increased availability of truly objective measures of physiological status.


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