The introductory section does not include a solid literature review describing credible research in the field. Lack of such review does not allow to link potential findings of the study to a wider framework of theoretical knowledge in the field. For the same reason, it is barely possible to identify gaps in the existing body of knowledge on the topic and thus adequately justify the need for another piece of research. No synthesis of relevant information on the previous studies is provided while the publications (newspapers, magazines, unpublished surveys) cited in the introductory section seemingly fail to provide the adequate background to the study.
Specific nature of the formulated research purposes raised a set of strict requirements to be addressed within a certain methodological framework. Quantitative approach, which implies use of standardized questionnaires and methods of data analysis, specific position of the researcher (considered external to the research), and replicability of results regardless of the context was reasonably considered to be the most relevant alternative. Although applicability of quantitative methods in health related research is limited due to the so-called 'decontextualization' phenomenon (models built using data obtained through quantitative methods do not take into account certain variables that act in the real world context (Patton, 2002)) this drawback does not apply to the study under review.
The authors employed cross-sectional research as the most appropriate design for their study which involved data from 10184 staff nurses and 232342 general, orthopedic, and vascular surgery patients discharged from the hospital between April 1, 1998, and November 30, 1999. Administrative data from 168 nonfederal adult general hospitals in Pennsylvania was analyzed. Nurses included in the sample were contacted via ordinary mail and asked to fill in the questionnaire designed by the authors. Data related to patient outcomes were retrieved from hospital databases.
Aiken and colleagues found out that each additional patient per nurse was associated with a 7% increase in the likelihood of dying within 30 days of admission and a 7% increase in the odds of failure-to-rescue. Also, each additional patient per nurse was associated with a 23% increase in the odds of burnout and a 15% increase in the odds of job dissatisfaction. Such findings are fully congruent with the assumption/hypothesis implied by the authors in the introductory section.
The authors seem to be fully aware of the major biases and limitations of their study and they explicitly acknowledge this fact by