Although other systematic reviews and meta-analyses of assessment tools for falls by hospitalized patients have been performed [9, 56, 57, 69, 106], ours is the first that includes only acute patients. This is particularly useful in clinical practice for identifying the behaviour of the instruments currently used exclusively in the hospital environment, where falls are among the most frequent adverse events , and thus are directly relevant to the development and implementation of safety policies in acute care hospitals.
Since V. Scott  and T.P. Haines  published their systematic reviews of fall risk assessment tools in 2007, there were no new updates focused on that instruments concerning acute hospitalized patients. The systematic review published by Oliver in 2009 focused only on the STRATIFY tool and was not limited to acute patients. In the present review, 9 [23, 25–27, 42–45, 48] of the 14 selected studies have been published since 2007, allowing an update of knowledge available on this topic. This is one of the strengths of this study. Another strength of this review is that contemplated studies assessing the psychometric properties of the fall risk assessment instruments.
This meta-analysis was carried out as a comparison of the Morse Fall Scale (MFS), the St. Thomas Risk Assessment Tool in Falling Elderly Inpatients (STRATIFY) and the Hendrich II Fall Risk Model (HFRM II). The results obtained showed the STRATIFY tool to be the best tool for assessing the risk of falls among hospitalized acutely ill adult patients, followed by MFS and finally HFRM II. STRATIFY produced the best values for sensitivity and had a specificity similar to that of MFS, and obtained the best values for DOR. In part, these results contradict those published in a recent meta-analysis focusing on MFS and STRATIFY , which found a higher sensitivity but lower specificity for the MFS with respect to STRATIFY. However, these results did not include the calculation of the DOR and some of the studies that were included were excluded from our analysis as not meeting the inclusion criteria. Moreover, we also considered another four studies published subsequently with data for these assessment tools [27, 42, 43, 48].
These three tools have been compared by their simultaneous application in a sample of hospitalized adult patients . In this study, HFRM II was found to be the most suitable for identifying the patients at high risk of falls, with a sensitivity of 70% and a specificity of 61.8%. However, in the present meta-analysis, HFRM II proved to be the worst of the three instruments considered, due to its lower sensitivity (0.628), specificity (0.640) and DOR (3.362).
In another study in which four risk assessment instruments (STRATIFY, Tinetti, Downton and Tullamore) were tested simultaneously in an acute patient hospital environment , STRATIFY was completed most easily and in the least time; furthermore, it also presented the best predictive validity, although it was the least sensitive of the four. The short time required to administer this assessment scale and the fact that it is readily understandable for medical staff are very relevant factors in an acute hospital setting where work loads are high and periodic reassessments of patients are advisable.
In previous systematic reviews of this question, one of the inclusion criteria was that the selected studies should conduct a prospective validation of assessment tools for falls [9, 69, 106]. In the systematic review and meta-analysis carried out by Haines in 2007  one of the practical implications described was that although retrospective evaluations are still valuable for generating initial results and identifying the tools and cutoff points that may be useful in clinical practice, less weight should be given to their results than to those obtained from prospective studies, with respect to selecting a detection tool for use in clinical practice. In coherence with this view, all the studies included in the present review conducted a prospective validation of the various instruments examined. Nine of the fourteen studies had been published since the completion of the above-mentioned systematic review. Moreover, the present analysis complies with one of the “gold standard” criteria described by Wyatt and Altman for such scales , although in none of the articles selected was a randomised controlled trial carried out, and this may be an area for improvement regarding the development of future research in this field.
Previous studies have argued that fall risk assessment performed only at the time of hospital admission does not identify changes in the patients’ clinical status during hospitalisation, although this is a common occurrence, especially among the elderly, who may become disoriented, agitated or lose functionality during hospitalisation, and thus be at greater risk of suffering a fall . The acute phase of the disease and changes in medication can affect both mobility and the physical and cognitive status, and therefore hospitals need an instrument that can be used quickly and easily so that repeated assessments of these patients may be carried out . In only four of the fourteen studies selected for this review was a reassessment conducted, whether on a weekly schedule [15, 27, 46] or following changes in the patient’s condition, after cognitive impairment, after significant changes in medication or after a fall . Although the meta-regression analysis with respect to this criterion showed no effect for HFRM II, and could not be performed for STRATIFY due to the lack of studies in which a reassessment of patients was performed, in the case of MFS, the reassessment produced a significant reduction in the DOR. This may be explained, in part, as the MFS losing predictive capacity when the risk of patients’ suffering a fall decreases, as their condition improves. In the only study in which a reassessment was carried out with MFS  the mean age of the patients was below 65 years (62.6). The condition of these younger patients would presumably improve over time, and so their risk is more difficult to identify with this scale. However, as discussed above, in only one of the studies in which MFS was tested was a reassessment performed. Thus, further research is needed, including reassessment both with MFS and with the other instruments in order to achieve a more realistic analysis of this circumstance. It should be borne in mind that, in general, it is difficult to accurately predict the risk of falls among hospitalized adult patients who are subjected to external risk factors, specific to the hospital environment and which are not taken into account by any of the assessment instruments described.
This review and meta-analysis may also be affected by the limitations of the primary studies analysed. First, knowledge of the number of patients suffering a fall is always dependent on the voluntary reporting of this fact by the healthcare staff, and so falls may occur that are not reported, which would to some extent invalidate the results obtained in these studies. Second, the review may be affected by contamination related to the implementation of other actions taken to prevent falls in the different environments studied, and by a possible Hawthorne effect. Moreover, limitations arise from the questionable quality of some of the studies selected: some offered no data on the age and/or sex distribution of the study population [15, 43, 46], or were deficient regarding the representativeness of the sample [22, 25, 44, 46–48] or regarding the blinding of the researchers [22, 27, 43–45]. Another possible limitation concerns the search language: in the present review, the search languages used were limited to English, Spanish and Portuguese, and four studies were excluded for this reason [102–105].
In short, despite the findings obtained, our analysis of the various studies clearly shows that the behaviour of these risk assessment instruments varies considerably depending on the population and the environment in which they are administered. In consequence, we cannot recommend the generalised adoption of any single method without its prior testing in the healthcare setting of the intended implementation. Moreover, it should be recalled that these instruments, or the actions taken including their use, will not be effective if healthcare personnel do not ensure patient safety procedures are followed, and this aspect remains to be investigated in the case of falls by hospitalized patients. A study of safety and security in Spanish hospitals reported that the majority of healthcare staff (77.8%) had not reported any event related to patient safety in the past year and that 95% had reported fewer than two such events . This aspect, noted above as one of the limitations of our study, and the question of compliance by personnel with procedures established to prevent adverse events, are issues which must be addressed in order to achieve an effective culture of safety within hospitals.