A National Scheme for Public Access Defibrillation in England and Wales - Essay Example

Critical Appraisal of Research Article 2009 Critical Appraisal of Research Article Colquhoun M. C., Chamberlain D. A., Newcombe R. G., Harris R., Harris S., Peel K., Davies C. S. and Boyle R. (2008). “A national scheme for public access defibrillation in England and Wales: Early results”, Resuscitation, Vol. 78, pp. 275 - 280 The study by Colquhoun et al (2008) is a pioneering effort of a national scale to measure and report “…the effectiveness of defibrillation by lay persons and the relative effectiveness of different public access defibrillation (PAD) strategies used in the UK” (p.276). The study rationale is absolutely clear and, in fact, it is surprising that a similar study had not been conducted prior to 2008 as the authors claim in their article. The issue of defibrillation by specially trained lay persons is not new to the medical literature though Colquhoun and colleagues provide only a brief insight into the existing research in the field. For example, there is substantial amount of past studies exploring the potential of PAD on survival and other outcomes of PAD (Pell et al, 2002; Culley et al, 2004; Engdahl, 2002), potential locations of AEDs (Becker et al, 1998), cost-effectiveness of different PAD strategies (Nichol, 2003), etc. The studies employed both qualitative (interviewing, observations) and quantitative (prospective randomized trials, surveys) methodologies to reveal comprehensive and multifaceted data on virtually every aspect of PAD. However, the authors provided a very concise review of prior studies, and instead of analyzing and synthesizing the most credible research in the field they only briefly stated the results of some surveys and analytical works. Therefore, the declaration made by Colquhoun and colleagues that the PAD project launched in the UK many years ago relied on next to no published evidence of PAD strategies’ potential effectiveness seems to be an intentional understatement meant to place extra emphasis on the importance of Colquhoun’s study. At the same time, there are really very few studies that seek to compare the effects of different PAD strategies within the framework of one study and particularly on the national scale in the UK. In this regard, the study can really be referred to as “…the first report of a national scheme that has incorporated PAD into mainstream health care provision” (p.279). Besides, expanding the body of knowledge and evidence pertaining to still developing PAD approach remains an important task in terms of resuscitation effectiveness improvement. The main source of data was standard report forms (Utstein form) filled in for any pre-hospital resuscitation attempt. Although the standard form contributed greatly to the uniformity of collected data, some essential variable such as the interval between cardiac attach and institution of basic life support and use of AED were estimated by the authors. As a result, there is a probability (though not great due to briefness of these estimated intervals) that the estimates might deteriorate study outcomes. However, as the authors reasonably note that the problem is common to all similar studies and the history of prior research demonstrates that the possible inaccuracy of estimates is not compromising. The substantial amount of data collected by the researchers was impossible to interpret without statistical data procession. For this purpose they employed well-known SPSS software. While the choice of statistical analysis instrument was absolutely reasonable (SPSS is a highly reputable analytical tool), Colquhoun and colleagues do not provide the reader with a clear list of variables analysed using SPSS. The tables and results section include only mentioning of the following variables: sex, age, survival, and delays to start of CPR and PAD. The quantitative methodology employs methods historically utilised in the natural (physical) sciences. Therefore, the main task of any quantitative study is to ensure validity and reliability of results (Dingwall et al, 1998). The concept of reliability as applied in quantitative research can be defined as: “The extent to which results are consistent over time and an accurate representation of the total population under study is referred to as reliability and if the results of a study can be reproduced under a similar methodology, then the research instrument is considered to be reliable” (Golafshani, 2003: 598). The issue of validity deserves particular mentioning in regard to the article being reviewed. Any study involves certain external (not related to the method employed) factors that may undermine internal validity of any research. The sum of such factors (e.g. poor representativeness, inaccurate or incomplete initial data, etc) causes the so-called ‘measurement error’ (Kaplan, 2004). The use of multidimensional statistical adjustments and other statistical instruments reduces the effects of this potential measurement error and, consequently, internal validity threats to minimum. The authors employ simple chi-square and Mann-Whitney significance tests to validate the binary variables mentioned above. However, no other statistical adjustments and/or possible variables (for example, prior history of illness, comorbidities, etc) were included in the study to take into account the majority of the factors that might confound the results. Therefore, certain measurement error is possible in the findings revealed by Colquhoun and colleagues. Besides, in terms of research design the study represents a survey with authors collecting historic data recorded at a variety of PAD locations. It is a typical descriptive design used to collect data about some particular characteristic or phenomenon (effectiveness of PAD in this case). The descriptive research design does not imply any manipulation of variables and does not attempt to establish/explore any causal relationship but only to determine the relationship between two or more variables (Dulock, 1993). This means additional statistical adjustments or variables might be unnecessary for the purposes of this study. The authors seem to be fully aware of the major biases and limitations of their study and acknowledge this fact by listing the most important of them. Analysis of the listed limitations suggests that the abovementioned possibility of measurement error was largely due to objective constraints, namely the fact that the researchers used data captured by a third party. Firstly, despite the requirement of the BHF to report every use of AED using a special standard form, it is not clear whether every volunteer followed this procedure strictly and recorded accurate and correct information. Secondly, strict confidentiality regulations in the UK made it almost impossible for the researchers to keep track of patients after successful PAD: it is not clear what happened with majority of such patients in future. Colquhoun and colleagues provide a strong synthesis of study results thoroughly listing every finding that have been labelled as statistically significant during statistical analysis. Reported results are fully congruent with the aim stated by the researchers in the introductory chapter: they illustrate absolute and relative effectiveness of public access defibrillation (PAD) for strategies used in the UK. Colquhoun and colleagues do not identify any parallels or links with the existing literature in the field to emphasize or explain their findings. However, this may be due to the fact that the study is really an innovatory one and there are simply no scientific publications that could be used for this purpose. Overall direction of the article suggests that the authors strongly believe their findings can be generalized to the whole population of potential PAD users. It should be noted that this belief seems to be reasonable granted the number of participants involved in the research: 1530 resuscitation attempts included in the survey ensures very good representativeness and implies great generalisability. And finally, the implications of the study are really essential in the UK context. First of all, the authors made a pioneering effort to develop a distinct measure of PAD effectiveness thus providing the much needed empirical underpinning for the recent initiatives of the Department of Health, the British Hart Foundation and other influential organisations to further increase the number of AEDs. Clearly, they failed to address the whole scope of issues and potential variables associated with PAD. Yet, they did manage to provide adequate evidence-based justification of the relationship between increased availability of AEDs both stationary and mobile and positive prognosis for victims of sudden cardiac attack. Overall, the study under review represents a solid piece of work written by the top-level professionals in the field of public health and resuscitation. In terms of the research methodology and design, the authors provide a good example of how quantitative method of surveying may be effectively used to reveal essential findings. Evidently, the study fails to achieve absolute clarity regarding the issue of PAD effectiveness and the effects of multiple variables that may potentially affect it. However, it was not the purpose of the study: it focused solely on the narrow aim formulated by the authors. This pioneering effort provides a good starting for further research meant to explore various aspects of PAD. References Becker L, Eisenberg M, Fahrenbruch C, Cobb L. (1998). “Public locations of cardiac arrest. Implications for public access defibrillation”. Circulation, 97: pp. 2106-2109 Colquhoun M. C., Chamberlain D. A., Newcombe R. G., Harris R., Harris S., Peel K., Davies C. S. and Boyle R. (2008). “A national scheme for public access defibrillation in England and Wales: Early results”, Resuscitation, Vol. 78, pp. 275 - 280 Culley, L. L., Rea, T. D., Murray, J. A., Welles, B., Fahrenbruch, C. E., Olsufka, M., Eisenberg, M. S., & Copass, M. K. (2004). “Public Access Defibrillation in Out-of-Hospital Cardiac Arrest: A Community-Based Study”. Circulation 109: pp. 1859-1863 Dingwall R, Murphy E, Watson P, Greatbatch D, Parker S. (1998). “Catching goldfish: quality in qualitative research”, Journal of Health Services Research and Policy 3: pp. 167-72 Dulock, H. (1993) “Research design: descriptive research”. Journal of Pediatric Oncology Nursing 10 (4): pp. 154–157 Engdahl, J. (2002). “Outcome after cardiac arrest outside hospital”. British Medical Journal 325: pp. 503-504 Golafshani, N. (2003). “Understanding Reliability and Validity in Qualitative Research”. The Qualitative Report 8 (4): pp. 597-607 Kaplan, D. (2004). The SAGE Handbook of Quantitative Methodology for the Social Sciences, London, Sage Nichol, G., Valenzuela, T., Roe, D., Clark, L., Huszti, E., Wells, G.A. (2003). “Cost Effectiveness of Defibrillation by Targeted Responders in Public Settings”. Circulation 108: 697-703 Pell, J. P., Sirel, J. M., Marsden, A. K., Ford, I., Walker, N. L., Cobbe, S. M., (2002) “Potential impact of public access defibrillators on survival after out of hospital cardiopulmonary arrest: retrospective cohort study”. British Medical Journal 325: p. 515 Read More