There is little information regarding physical activity of hospitalized patients. To our knowledge, this is one of the largest studies measuring physical activity by accelerometry in older patients hospitalized with acute medical illness. According to our results, older hospitalized patients are inactive most of the time, and their PA is distributed into daily patterns.
Physical activity levels and distribution throughout the day
Patients spent a median of approximately 1 hour/day on PA, a value lower than the 4.2 hours/day reported by Lim et al.’s study (12), who analyzed locomotion in 38 acutely hospitalized older patients (median age of 87.8 years). Conversely, another study reported only 43 min per day spent standing or walking (32) in a sample of 45 hospitalized older patients (median age 74.2 years) capable of walking independently pre-admission. Another study also reported that 30 older patients (median age 83.6 years) spent less than an hour between 9 am and 5 pm in an upright position and nearly 50% of the day lying down (19). Finally, a study reported even lower durations spent walking (7 min/day) and standing up (35 min/day) in 100 older patients (median age 84 years) (17).
Interstudy comparison and reproducibility is very difficult because of the use of different thresholds and different PA metrics. Older hospitalized patients are characterized by very low PA levels, and thresholds to define PA in this population are rare and differ according to studies. In our study, PA levels were defined according to Bakrania et al (26), light PA being defined by an acceleration ≥30 mg, whereas in the study of Lim et al. (12), a 1-min mean acceleration ≥12 mg was selected to define PA. Thresholds similar to those proposed by Lim et al. have been reported in free-living older people (median age ≥65 years) (13, 33) and younger (26, 34) populations. Still, other thresholds for light PA, developed and validated in laboratory calibration or in free-living populations, are usually ≥40 mg (35-38). Analysis of our recordings with a thresholds of ≥85 mg as proposed by White et al. (35), ≥30 mg as proposed by Bakrania et al. (26), and ≥12 mg as proposed by Lim et al. (12) led to PA levels of 6, 65 and 175 minutes/day, respectively (supplementary table 4). Hence, further studies are necessary to define the threshold that correctly identifies sedentary hospitalized patients at risk of complications.
The distribution of PA according to the period of day showed peaks between 8 and 10 am, at 12 am and at 6 pm. Our findings replicate Lim et al.’s observations (12) in a larger sample and suggest that older inpatients mobilize primarily during meal (eating) periods.
Physically active versus inactive patients
Compared to physically active patients, physically inactive patients more frequently reported the use of walking aids 2 weeks before hospitalization, were more frequently admitted for a reason associated with functional decline, and had a higher dependency level according to Barthel Index score. These findings are consistent with other studies (8, 39 , 40 ). Moreover, our results suggest that initial evaluation of patients using these metrics could help to identify patients in need of mobilization during hospital stay (9).
Our results suggest that increased efforts are necessary to mobilize hospitalized patients. Nevertheless, the magnitude of efforts needed to achieve an adequate amount of PA during hospitalization may exceed the existing resources of the hospital. Future studies should try to estimate not only the minimum amount of PA needed to prevent increased in-hospital morbidity or length of stay, but also the optimal conditions necessary to deliver mobility interventions.
Physically active patients were less likely to have cognitive impairment/confusion. A possible explanation is that patients with declining cognitive function reduce their PA in an unknown environment. Our findings are in agreement with a Danish study including 48 older patients (mean age 84 years), where cognitive impairment at admission was associated with lower PA levels during hospitalization (41). Conversely, a Norwegian study including 38 older patients (median age 83 years) found no association between cognitive impairment and PA (16). Indeed, most studies assessing PA in older hospitalized adults excluded patients with cognitive impairment (11, 12, 39, 42, 43). Overall, our results suggest that greater PA levels might be associated with a lower risk of cognitive impairment/confusion, a finding in agreement with recommendations for preventing this status (44).
Implications for clinical practice
Our results strengthen the available evidence that hospitalized older patients move very little and that some indicators such as the Barthel Index assessed at admission are relevant to identify patients at risk of inactivity during hospital stay. An interesting finding were the peaks of PA during mealtimes, also reported in another study (12). Hence, a possible way to favor patients’ locomotion would be to serve meals in common rooms instead of in hospital beds. Other alternatives include mobilization by family members or volunteers (if the patient’s condition allows it) to compensate for lack of resources (45). This alternative was also recently used in an interventional study aiming to reverse the functional decline associated with acute hospitalization in very old patients (46).
Strengths and limitations
The strengths of this study are its large sample size, its broad inclusion criteria, the use of accelerometers to assess PA and the large number of PA hours recorded. Regarding sample size, this study is the largest when compared to other studies in Europe (12, 13, 16-18, 41), the USA (20, 21, 32) and Australia (14, 19). Regarding inclusion criteria, and contrary to previous studies (12, 32, 47, 48), we included patients with cognitive impairment/confusion as they are at increased risk of post-hospitalization functional decline (28, 39). Finally, PA was assessed using accelerometers, which are considered superior to pedometers (49) and allow data analysis using different algorithms.
This study also has some limitations. First, the study was conducted in a single university hospital, which might limit generalizability, as patients attending a university hospital may present more comorbidities or more severe diseases than patients attending a general hospital. Hence, it would be important that this type of study be implemented in other settings. Second, some recordings were very short (<24 hours) and could not be used, or had a high percentage of accelerometer non-wear time. Still, our findings are similar to another study that used the same methodology and included all available data, and findings were similar when patients with a high non-wear time were excluded (supplemental tables 2 and 3). Third, patients were free to choose on which side they wore the accelerometer; this might lead to differences, as the dominant hand was not systematically used. Still, a previous study (24) showed no difference in physical activity measurements when comparing dominant to non-dominant wrist and, similarly, no differences were found in our study (supplementary table 5). Finally, our approach did not allow differentiating between PA in bed or elsewhere. Further studies could implement PA assessment by combining accelerometry with manual or automatic recording of location.