Older adult non-conveyed patients (≥65 years) have significantly different clinical characteristics and attributes than younger patients (18–64 years). The findings indicate that the dispatch priority levels are generally lower among older adults. There is a greater incidence of non-conveyance during daytime, and older adult non-conveyed patients are more often assessed by ambulance clinicians to have nonspecific complaints and less often symptoms related to trauma. Despite the lower dispatch levels and symptoms categorised as nonspecific, all measured short-term outcomes over a 7-day period following non-conveyance were more common among older adult patients. Approximately one in five older adult non-conveyed patients was hospitalised within 7 days following non-conveyance. Overall, the increased risk of hospitalisation and mortality following non-conveyance among older adult patients is important new knowledge which raises questions pertinent to patient safety.
This study is one of very few studies to have investigated the general older adult non-conveyance population and to have comparatively evaluated the short-term outcomes with those in younger non-conveyed patients. One of the most important findings from this study is the higher risk of subsequent and adverse events among older non-conveyed patients. The overrepresentation of older adult patients among the lower dispatch levels in combination with an overall higher risk of subsequent events following non-conveyance indicates a complexity which accompanies both symptom presentation and communication in the older adult patient population. These findings may be an effect of age, though age is unaccounted for in the regional medical non-conveyance guideline and the triage system which is currently in use. Older adult non-conveyed patients were more often assessed with nonspecific or vague presenting symptoms than younger patients. In line with a previous study , patients assessed with nonspecific presenting symptoms were at higher risk of ED visits and hospitalisation following non-conveyance. Conditions related to infectious diseases, such as sepsis, have high mortality rates among older adult patients . However, we cannot conclude from the results of this study as to which findings in older patients presenting with infectious symptoms conferred the highest mortality risk following non-conveyance, though the missed identification of sepsis could be a possible explanation to our findings. Furthermore, the increased risk of adverse events among older patients with psychiatric symptoms calls for further studies which investigate this vulnerable group of patients.
Furthermore, similarly as in a previous study , the occurrence of at least one abnormal vital sign was associated with an increased likelihood of an ED visit and hospitalisation, but not mortality. Renewed contact with the ambulance service and ED visits among older adult non-conveyed patients is relatively common , although comparisons with earlier non-conveyance studies are difficult to perform due to significant heterogeneity between these studies . The follow-up time varies greatly between earlier non-conveyance studies: the longer the follow-up time, the greater is the risk that the patient is likely to be affected by other factors than the one which was initially associated with the non-conveyance assessment [7, 8]. There is an absence of consensus with regard to relevant outcome measures for non-conveyed patients, and those must be selected appropriately to capture the specific needs of non-conveyed patients. As shown in this study, patient risk factors had a variable strength of association with the different short-term outcomes which were studied. This implies the need for future research on relevant outcome measures for non-conveyed patients, and what is to be considered as an adverse event in a specific non-conveyance context.
To our knowledge, this is the first study to investigate the association of abnormal vital signs with short-term outcomes among older adult non-conveyed patients. Marked variation was noted among the different age groups of older adult non-conveyed patients. However, the validity of abnormal vital signs in recognising deterioration among older patients has been questioned earlier. The identification of clinical status deterioration among older patients most frequently include other indicators, such as comorbidities, polypharmacy, and behavioural changes and everyday capabilities . The abovementioned findings imply the need for further studies to enhance the knowledge of the potential clinical significance of abnormal vital signs and other indicators in the non-conveyance context. An oxygen saturation level < 95% and systolic blood pressure > 160 mmHg had a significantly higher association with adverse outcomes among all groups of older adult non-conveyed patients in this study. An elevated systolic blood pressure among older adult patients is a relatively common clinical finding and is associated with an increased risk for the development of several different diseases (e.g. coronary heart disease and cerebrovascular disease) . Nonetheless, the results of this study are exploratory in nature and, thus, we cannot definitively conclude the clinical significance of the abnormal oxygen level and elevated systolic blood pressure. Cognitive impairment among older adult patients who visit the ED is associated with adverse outcomes . A GCS score < 15 was associated with adverse outcomes in three out of four groups of older non-conveyed patients in this study.
Limitations and strengths of this study
This study has limitations which affect its generalisability and validity. Though the study setting included the whole region’s ambulance service, the study should be considered as a single-region study; therefore, the results might not be applicable to other national or international ambulance services and non-conveyance populations. The use of medical records as the data source is associated with methodological challenges, as they were not designed for research purposes, thereby creating unfavourable circumstances from a research perspective. For example, the medical records lacked information on possible patient referral, such as referral to own transportation to ED (e.g. patient’s own car). Moreover, decreasing the risk of outcome bias through misclassification of exposure resulted in the exclusion of ED visits as a possible adverse event. We therefore believe that (unplanned) hospitalisations within 7 days more accurately reflect possible patient safety risks following non-conveyance. Nonetheless, the associations identified in the multiple regression analyses should be considered preliminary. Other studies have identified comorbidities as a risk factor for adverse events [34, 35]. Unfortunately, our data set did not contain information on the patient’s comorbidities. Furthermore, the data set is from 2015 and, therefore, even if the standard of the regional non-conveyance medical guideline, ambulance clinicians’ formal competence, and education has not changed substantially, the results cannot account for any changes which may have influenced the short-term patient outcomes since 2015. When investigating patient risk factors, the short-term outcome mortality was excluded as a dependent variable from our regression models due to the very few events in our data set. Moreover, using mortality as a short-term outcome requires several additional measures to minimise the risk of misclassification of exposure, and includes trying to connect the cause of death with the reason for non-conveyance by including the death certificate in the analysis, which we could not access in this study. The same reasoning applies for hospitalisation. We did not have information on the reasons for hospitalisations, which could be considered a limitation of this study.
Notwithstanding these limitations, this study has several strengths. Our data set comprised all non-conveyed patients in the study setting area during 2015, thereby reducing the possible selection bias. The use of the regional database VAL as a validated outcome register is associated with several methodological advantages . The risk which accompanies the database linkage was minimised through the comprehensive content of VAL with regard to in- and outpatient care in Region Stockholm. Furthermore, the patient’s anonymity was maintained through the database linkage with the use of ambulance assignment numbers. This was one of very few published non-conveyance studies in which the association of abnormal vital signs with short-term outcomes among older adult non-conveyed patients was investigated. This was made possible through the use of ambulance medical records wherein the vital signs of non-conveyed patients were documented.
Implications for clinical practice and research
The results of this study have important implications for clinical practice and future research. Ambulance stakeholders, health-care policymakers, educational institutions, and ambulance organisations and its clinicians should all be aware of the increased frequency of subsequent and adverse events in older adult non-conveyed patients. This study offers new insight into the association between abnormal vital signs and adverse events. A possible future clinical implication of the study findings is the implementation of age-adjusted assessments within triage systems which are specifically developed and validated for non-conveyance. Further modelling research is necessary to achieve satisfying levels of patient safety through the use of more accurate triage systems and, thereby, the creation of more favourable circumstances for ambulance clinicians to perform these most often difficult assessments. Further research is required to identify and determine relevant outcome measures for different non-conveyance populations. Moreover, there is a need for further research into the patient perspective with regard to subsequent and adverse events following non-conveyance. Despite the increasing research within the field of non-conveyance, the assessment of older adult non-conveyed patients is hindered by several aggravating circumstances and clinical challenges. Thus, this study could inspire and provide a framework which supports further studies in the field.