Discussion
Little is known about the severity and duration of hospitalisation-associated disability after acute infectious disease in older adults. Our study found that 60.2% of hospitalised older patients with pneumonia experienced unfavourable—poor (substantial decline from baseline) and very poor (persistently low)—trajectories and that the probability of following the unfavourable trajectory increased exponentially from 11.8% in robust patients, 25.6% in pre-frail patients, 92.5% in mild-to-moderately frail patients, to 100% in severely frail patients. Although older adults with frailty had more severe pneumonia, the association of frailty with unfavourable trajectory was independent of pneumonia severity. These results highlight the high incidence and lasting duration of hospitalisation-associated disability in older adults with pneumonia.
Previous studies have shown that hospitalisation-associated disability in older adults was associated with change in functional status prior to hospitalisation,26 frailty and cognitive decline at hospital admission.27–31 Acute illness or injuries such as a fall that results in a hospitalisation increases the risk of new or worsening disability.30 32 Gill et al found that in older adults, pre-hospitalisation disability and frailty are associated with an increased risk of functional decline and decreased ability to recover post-hospitalisation.30 32 Results of our study confirm findings of previous studies while adding to the literature knowledge that is specific for hospitalisation due to pneumonia, a common cause of hospitalisation in older adults. Similar to the functional trajectories found by Gill et al after hospitalisation due to falls,32 we found various functional trajectories older adults experience 6 months after hospitalisation due to pneumonia. Functional trajectories 6 months after admission due to acute respiratory failure were reported in recent studies,33 34 however, the patient population was not specific to older adults and baseline clinical characterisation of patients were not present.
In our study, we used frailty as a clinical measure to characterise the baseline health status of patients. The FI takes into consideration various health domains that are routinely assessed in an evaluation of older patients, such as medical history, cognitive status and Katz or Barthel ADL index. The average administration time in our study was 15–20 min without cognitive assessment and 30 min with cognitive assessment (which was not feasible in 60% of the patients). The FI allows gradation of frailty severity (as opposed to just the presence or absence of frailty) and a more holistic and complete assessment for comprehensive care planning. Cognitive impairment is important to capture as it has been shown to be associated with worse disability after a hospitalisation in older adults.27 Our findings suggest the utility of FI to assist in anticipatory discharge planning after an acute hospitalisation due to pneumonia.
Commonly used pneumonia severity measures, CURB-65 and PSI, were developed to predict 30-day mortality.35 These measures do not take baseline functional status into consideration. Functional status and recovery are important outcomes to many older patients who survive acute hospitalisation for pneumonia. Chen et al showed that PSI was associated with delayed discharge and functional decline in older patients with pneumonia.36 In our study, CURB-65 and PSI were scattered across all trajectory groups and did not reliably predict long-term functional status as compared with FI. These results suggest that FI should be used in conjunction with pneumonia severity scores to provide appropriate hospital and post-acute care in hospitalised older patients with pneumonia. In addition to long-term functional status, the four trajectory groups also correlated with in-hospital outcomes. Worse trajectory groups had higher rates of ICU admission, prolonged hospitalisation and long-term care institutionalisation. Though patients in the excellent and good trajectory group composed 20.6% of ICU admissions and 50.4% of prolonged hospitalisation, they only made up 5.5% of the patients who went to long-term care institutions. This suggests that though patients in the excellent and good trajectory group may have arduous hospitalisations, they may be able to recover and be discharged home rather than to a long-term care centre. By being able to predict the trajectory of patients using the FI, this could have important clinical implications in terms of deciding management of older patients with pneumonia. Since ending up in long-term care institutions is an important decision-making factor for patients, the ability to predict who could avoid this outcome based on FI could guide aggressivity of pneumonia management.
Our study suggests a possible window of opportunity to implement rehabilitation programmes to prevent the loss of functional status, especially for those who are pre-frail or mild-to-moderately frail on admission. Of the four functional status trajectories, the poor trajectory group experienced a substantial decline in functional status within the first month of the admission and persistent disability afterwards (figure 1). A majority of patients in this group were pre-frail (11 of 58 patients) or mild-to-moderately frail (34 of 58 patients). Whereas previous studies have looked at the effect of implementing rehabilitation programmes for ICU, chronic obstructive pulmonary disease and emergency department patients,37–39 no studies examined interventions for older patients based on frailty levels immediately following an acute hospitalisation. Based on our findings, interventions targeting pre-frail or mild-to-moderately frail older patients may achieve a larger reduction in hospitalisation-associated disability.
Our study has several strengths and limitations. Major strengths of our study include a prospective cohort design to assess functional recovery in an acute care setting over an extensive 6-month period with high rates of successful follow-up. Additionally, the present study enrolled 201 patients with a fairly even distribution of baseline frailty. However, the study has a few limitations that merit consideration. First, functional status was defined by self-reported telephone interviews, rather than through clinician-based observation. Second, our results may have limited generalisability and external validity given that the present study employed a single centre prospective cohort, which was comprised entirely of an older Korean population. It is possible that functional recovery in older results may differ in a more diverse patient population; hence, we recommend that clinicians weigh geographic and situational differences specific to their healthcare infrastructure in their interpretation of our results. Additionally, our cohort was restricted to older adults who were hospitalised due to pneumonia, and therefore, our results could be limited to the applications of a single disease, notwithstanding the fact that pneumonia is associated with significant mortality and morbidity in many older adults.5 40 Finally, a small minority of older adults, such as patients with cancer included in the robust frailty group, may experience temporal variations in post-baseline frailty, and hence, in turn, could interfere with the predictive ability of our trajectory scores.
In conclusion, our study showed that 6 of every 10 older patients who were hospitalised for pneumonia had substantial loss or persistent severe impairment in functional status. Frailty status on admission was a strong determinant of post-hospitalisation functional status trajectory, independently of pneumonia severity. These results can be useful to develop interventions and prioritise resources to prevent hospitalisation-associated disability in hospitalised older patients with pneumonia.