Letters to the Editor Measurement of Patient Satisfaction To the Editor: The article by Fung and Cohen (1) is timely and comprehensive but overlooks several important issues. The selection of the studies reviewed lacked a systematic method, as suggested by Cook (2). Of the 20 studies, 11 did not use an instrument specific to satisfaction with anesthesiology but, rather, global measures of patient satisfac- tion with healthcare services in general. The authors did not mention the control of social desirability (SD) in the list of confounding variables related to measurement of patient satisfaction. If an individual is strongly motivated to present him- or herself in a way that society regards as positive, responses to selected items may be distorded. Thus, SD must be controlled to eliminate bias and yield valid results (3). Finally, one study considered rigorous (4) presented psychomet- ric flaws: The test-retest interval was only 4 days, measuring more memory than stability of the instrument; subjects were influenced by SD: 90% answered “yes” to the question “I like my anesthetist,” and presence of anesthesiologists during data collection violated patients’ right to confidentiality. The time has come to evaluate patient satisfaction with anesthe- sia, and we agree that only rigorously conducted surveys will yield meaningful outcomes. Sylvie Le May, MSc Jean-Franc ¸ois Hardy, MD Department of Anesthesia Montreal Heart Institute Montreal, Quebec, Canada Marie-Christine Taillefer, BSc Gilles Dupuis, PhD Department of Psychology Universite ´ du Quebec a ` Montreal Montreal, Quebec, Canada References 1. Fung D, Cohen MM. Measuring patient satisfaction with anesthesia care: a review of current methodology. Anesth Analg 1998;87:1089 –98. 2. Cook D. Systematic reviews: the case for rigorous methods and rigorous reporting. Can J Anaesth 1997;44:350 –3. 3. DeVellis RF. Scale development: theory and applications. London: Sage Publications, 1991. 4. Dexter F, Aker J, Wright WA. Development of a measure of patient satisfaction with monitored anesthesia care: The Iowa Satisfaction with Anesthesia Scale. Anesthesiol- ogy 1997;87:865–73. In Response: We appreciate the interest and comments made by Lemay et al. A systematic review of the literature in patient satisfaction is difficult because investigations into this area are inconsistently de- fined, disunified, and frustratingly unfocused in both intent and methodology. To acquire the 20 studies we reported, several differ- ent search strategies of MEDLINE were needed. We deliberately limited targets to those studies that had measured patient satisfac- tion in relatively large patient samples because these were most likely to have measured patient satisfaction as a primary outcome and used instruments that would be most informative to the issue of patient satisfaction measurement in anesthesia. Because we are investigators in the field of anesthesia research, we included existing studies despite the variable quality, as these are the only studies to look at patient satisfaction with anesthesia care. We also chose to include large anesthesia surveys that used questions that we knew only indirectly measured patient satisfac- tion (e.g., asking whether patients would return to have the same anesthetic again or would undergo day surgery again). These ques- tions help to demonstrate the existing latitude and corresponding ambiguity inherent in past measurements of patient satisfaction and reinforce the common limitations seen in all studies. Excluding them would not have changed the message. Social desirability is one of a wide range of potential factors that has been proposed as potential confounders of patient satisfaction (1). We chose to highlight a few major confounders that undermine the validity of current measurements in anesthesia care; more com- prehensive lists of confounders are available elsewhere (1,2). Unfor- tunately, even in other healthcare domains, only a few confounders have been directly studied. Until they are, their influence is uncer- tain. For example, although preexisting expectations had great the- oretical influence on patient satisfaction, their confounding effect when measured has, so far, been small (2). One of the major tasks facing future anesthesia investigators in patient satisfaction will be to decide which factors to control. Finally, we did not mean to suggest that the studies of Whitty et al. (3) or Dexter et al. (4) be viewed as models of rigorous psycho- metric methodology. Rather, as we stated in the review (5), these studies were the first to use psychometric methodology of any degree of rigor and, even so, provide evidence that greater meth- odological rigor will yield instruments of greater value to anesthe- siologists. For examples of truly rigorous use of psychometric meth- ods in questionnaire development in healthcare, one should turn to the efforts of Ware et al. (6) or Meterko et al. (7) in ambulatory and hospital care. Donald Fung, MD, FRCPC North Bay General Hospital North Bay, Ontario, Canada Marsha Cohen, MD, FRCPC Dept of Health Administration University of Toronto Toronto, Ontario, Canada References 1. Pascoe G. Patient satisfaction in primary health care: a literature review and analysis. Evaluation Program Plan 1983;6:185–210. 2. Aharony L, Strasser S. Patient satisfaction: what we know and what we still need to explore. Med Care Rev 1993;50:49 –79. 3. Whitty PM, Shaw IH, Goodwin DR. Patient satisfaction with general anaesthesia. Anaesthesia 1996;51:327–32. 4. Dexter F, Aker J, Wright J. Development of a measure of patient satisfaction with monitored anesthesia care. Anesthesiology 1997;87:865–73. 5. Fung D, Cohen M. Measuring patient satisfaction with anesthesia care: a review of current methodology. Anesth Analg 1998;87:1089 –98. 6. Ware JEJ, Snyder MK, Wright WR, Davies AR. Defining and measuring patient satisfaction with medical care. Evaluation Program Plan 1983;6:247– 63. 7. Meterko M, Rubin H, Ware JEJ, et al. Patient judgements of hospital quality question- naire. Med Care 1990;9(Suppl):S1– 44. Continuing Inflammation Does Enhance Spinally Mediated Antinociception by Neostigmine in the Rat Model To the Editor: We and others have suggested that spinal analgesia mediated by intrathecally administered neostigmine depends on the level of endogenously released acetylcholine (1–3). We hypothesized that tonic persistent pain would enhance acetylcholine concentration within the spinal cord and that spinally applied neostigmine would thus increase its analgesic efficacy under painful conditions. Ac- cordingly, in a previous studies, we also observed a tendency to- ward enhanced antinociception in an animal model of tonic persis- tent inflammatory pain (1). We have now further elucidated the hypothesis that pain by itself will result in augmented antinocicep- tion by intrathecal (IT) neostigmine. ©1999 by the International Anesthesia Research Society Anesth Analg 1999;89:255–67 255