Assessment of Functional Mobility After COVID-19 in Adults Aged 50 Years or Older in the Canadian Longitudinal Study on Aging

Key Points Question What is the association of a COVID-19 diagnosis and mobility and physical function among community-living middle-aged and older Canadians during the initial pandemic lockdown in 2020? Findings This cohort study of 24 114 participants found that community-living middle-aged and older adults with confirmed, probable, or suspected COVID-19 had nearly 2-fold higher odds of worsening mobility and physical function compared with adults without COVID-19, although most participants with COVID-19 had mild to moderate disease and were not hospitalized. Meaning These findings suggest that individuals with mild and moderate COVID-19 who were predominantly not hospitalized experienced deficits in functional mobility compared with those without COVID-19.


Introduction
The World Health Organization (WHO) declared COVID-19 a pandemic on March 11, 2020, and as of December 2021, there have been more than 262 million confirmed cases and more than 5.2 million deaths globally. 1 In response to COVID-19, local and national governments introduced multiple public health measures, including limitations and restrictions on sizes of gatherings, self-isolation and quarantine of known cases and close contacts, extended lockdowns, closure of nonessential services, and travel restrictions to prevent the spread of infection and mitigate its population health effects. 2 Nevertheless, the ongoing pandemic and the associated public health measures have significant consequences for all populations and especially for older adults. 3 Studies of clinical sequelae of COVID-19 in hospitalized cohorts have found an increased risk of neurological and psychiatric diagnoses and persistent physical and mental health symptoms associated with COVID-19; however, mobility and functioning outcomes are not well characterized. Even less is known about mobility and function in nonhospitalized samples of community-dwelling older adults. 4,5 Mobility is well recognized as an essential component of well-being and an important determinant of healthy aging. A developing body of literature has shown that patients with severe COVID-19 who survived hospitalization report ongoing symptoms and physical limitations up to several months after discharge. [6][7][8][9] There is also some emerging research to suggest that even mild to moderate COVID-19 can have negative ongoing functional associations for nonhospitalized patients. 10,11 However, a major criticism of this early work is the use of convenience sampling (eg, recruitment via social media) and lack of control or comparison groups. In addition, the associations of preexisting sociodemographic and health characteristics in community-dwelling individuals with changes in mobility and functioning from COVID-19 remain to be elucidated. We hypothesized that individuals with confirmed or probable and suspected COVID-19 will be more likely to report worsening of mobility and physical function compared with those without COVID- 19. The purpose of this study was to examine the association between a COVID-19 diagnosis and change in mobility and physical function among middle-aged and older adults who were enrolled in the Canadian Longitudinal Study on Aging (CLSA) COVID-19 study.

Methods
This cohort study was approved by the Hamilton Integrated Research Ethics Board and by research ethics boards of all the participating institutions across Canada. Informed consent was obtained from the participants. This study follows the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cohort studies.

Study Design and Participants
The CLSA consists of a national sample of 51 338 adults in Canada aged 45 to 85 years at the time of recruitment (baseline 2011-2015). Participants were recruited from across the 10 provinces and are followed-up every 3 years. Individuals residing in Canada's 3 territories, on First Nation reserves, or in long-term care facilities, as well as members of the armed forces, those who were unable to communicate in English or French, and those with severe cognitive deficits were not eligible to participate in the study. A core set of information was collected from all participants by questionnaire. The first follow-up assessments were completed among 48 893 participants from 2015 to 2018. Further details on the CLSA study design and methods have been described elsewhere. 12,13 In response to the onset of the COVID-19 pandemic, the CLSA launched the COVID-19 Questionnaire Study on April 15, 2020

Mobility and Physical Function
Changes in mobility since the start of the COVID-19 pandemic were assessed using global rating of change in mobility scales in the COVID-19 exit questionnaire. Consistent with the International Classification of Functioning, Disability and Health definition, participants were asked to report changes in their mobility in 3 domains: ability to move around the home, engage in housework, and engage in physical activity on a 5-point Likert scale ranging from 1 indicating much worse to 5, much better. In this analysis, each outcome was dichotomized into either worse or not worse. Selfreported physical function for 3 specific functional tasks was assessed at CLSA first follow-up and the COVID-19 exit survey. Participants were asked to report whether or not they experienced difficulty in standing up after sitting in a chair, walking up and down a flight of stairs without assistance, and walking 2 to 3 neighborhood blocks. Participants who experienced difficulty were further probed about the degree of difficulty, with response options being a little difficult, somewhat difficult, and very difficult (eTable 2 in Supplement 1). Responses for each item from the CLSA first follow-up and the COVID-19 exit questionnaire were compared to create a change variable with categories of worse and not worse.

Assessment of Covariates
Covariates included age at COVID-19 exit questionnaire and prepandemic variables from CLSA first follow-up, including sex, annual household income (categorized as <CAD$50 000, CAD$50 000 to <CAD$100 000, and ՆCAD$100 000), dwelling type (house including single detached, semidetached, duplex or townhouse; apartment or condominium; or other form of housing, including seniors' housing, institution, mobile home, hotel, rooming or lodging house), living area (urban or rural), smoking (never, former, or current smoker), physical activity (adequate or low activity), nutritional intake (high risk or not at risk), and number of chronic conditions from 10 disease categories, including musculoskeletal, respiratory, cardiovascular, endocrine-metabolic, neurological, gastrointestinal, genitourinary, ophthalmologic, renal, and cancer, which were added and categorized as less than 3 or 3 or more conditions. Race and ethnicity was self-reported, and it was included as a covariate in the sensitivity analysis.
The Physical Activity Scale for Elderly was used to assess participants' physical activity levels. 16 Based on the World Health Organization's age-specific recommendations, adequate physical activity was classified as engaging in at least 150 minutes of moderate-intensity or at least 75 minutes of vigorous-intensity physical activity per week. 17 Nutritional behavior was assessed using the Seniors in the Community: Risk Evaluation for Eating and Nutrition tool. 18 Using previously validated cutoff of a score less than 32 was identified as high risk. 18

Statistical Analysis
Descriptive statistics for all participants were presented as frequency and percentage. CLSA first follow-up data were used to impute a variable that was not assessed in the COVID-19 baseline and exit surveys, and COVID-19 baseline data were used to impute a variable that was not assessed in the COVID-19 exit survey. Multivariable logistic regression models were used to examine the association between COVID-19 status and change in mobility and physical function outcomes. All multivariable models were adjusted for the prepandemic covariates, since they are known to be associated with increased risk of COVID-19 and poor functional mobility outcomes. Unadjusted and adjusted odds ratios (aORs) and 95% CIs were reported. Statistical analyses were conducted using SAS software

Results
Among 51  We also tested models after additionally adjusting for ethnicity, number of people living in the same household, social participation, and alcohol consumption. These variables did not have any significant associations and did not confound the association between COVID-19 and mobility and functioning; thus, they were subsequently excluded (eTable 5 and eTable 6 in Supplement 1). We also explored interactions of COVID-19 status with age, sex, household income, and number of chronic conditions (eTables 7-12 in Supplement 1). Overall, participants with COVID-19 characterized by older age, lower total income, living in an apartment or condominium rather than a house, having 3 or more chronic conditions, inadequate physical activity, and poor nutritional intake also reported worsening for many of the mobility and functioning outcomes (Tables 2 and 3)

Discussion
This cohort study is the first study, to our knowledge, to evaluate the associations of confirmed, probable, or suspected COVID-19 with the mobility and functioning of a community-based sample of middle-aged and older adults. Our results showed that community-dwelling individuals who reported confirmed, probable, or suspected COVID-19 had higher odds of worsening mobility since the start of the pandemic and worsening physical function since the CLSA first follow-up compared with those without COVID-19. Importantly, in a population-based study with a built-in comparison group, these findings highlight the burden of mild to moderate COVID-19 not requiring hospitalization on physical health in community-living people.
Although there is a growing body of research showing that hospitalized patients with COVID-19 experience problems with physical functioning up to 6 months after discharge, there is still a dearth of literature on nonhospitalized patients with less severe illness. 5,6,19,20 Anecdotal reports, patient accounts on social media, and some preliminary research with convenience samples, have suggested that many patients who experience even mild COVID-19 have persistent and troublesome symptoms, including impaired physical function after their initial illness. 10,11,21 There is an ongoing effort by both health professionals and patients alike to recognize long COVID as a long-term condition and to increase access to treatments and rehabilitative care. [22][23][24] Our findings confirm that individuals with COVID-19 who did not require hospitalization were more likely than those without COVID-19 to experience worsening of overall mobility since the start of the pandemic and a deterioration in physical function at the COVID-19 exit survey compared with the CLSA first follow-up. Research suggests certain coronaviruses can cause inflammatory damage to the central nervous system tissue. 25 Studies conducted in individuals with severe acute respiratory syndrome and Middle East respiratory syndrome reported prolonged fatigue, sleep disturbances, and changes in cognition after recovery from infection. [26][27][28] Similar symptoms have been reported by individuals after COVID-19. [28][29][30] Some evidence suggests that the SARS-CoV-2 can cause neuroinflammation and inflammation in other parts of the body, resulting in neuronal degeneration and release of proinflammatory cytokines, which may explain the subsequent chronic fatigue and functional mobility impacts experienced by many individuals after COVID-19. [28][29][30] It is also possible that public health recommendations for quarantine and self-isolation for individuals who have test results positive for COVID-19 restricted physical activity and may have exacerbated the mobility and physical function decline. 31,32 Further, our results showed that sociodemographic risk factors and having 3 or more chronic conditions were associated with a decline in mobility and/or functioning. These risk factors have been associated with severe COVID-19 and its complications, 33,34 and our findings indicate that these risk factors are also negatively associated with physical health outcomes in community-dwelling individuals, some of whom may have mild to moderate COVID-19. Therefore, older adults in these subgroups who may become ill with COVID-19 should be prioritized when planning interventions.
Taken together with previous work, our results suggest a need for approaches to effectively restore functional mobility to predisease levels after COVID-19. It is recommended that approaches that promote gradual activity and enhance social, cultural, and financial support may help with managing post-COVID-19 conditions. 35 The strengths of this study include the timing of data collection in the midst of the COVID-19 pandemic. Additionally, our use of a large sample of community-living adults to examine changes in function and mobility relative to a COVID-19 diagnosis make our findings more nationally generalizable.

Limitations
Our study has several limitations that should be considered when interpreting the findings. COVID-19 status was classified based on self-reports, and not all cases were confirmed with testing. The number of participants with confirmed or probable COVID-19 was small, which may have resulted in lower statistical power to examine associations for this group. Furthermore, the exact timing of COVID-19 diagnosis in relation to mobility decline or duration of functional mobility deficits was not assessed in our study. Functional mobility was not assessed using performance-based tests and therefore the mobility outcomes may be prone to recall bias. Additionally, individuals at risk of experiencing worsening of mobility may be more likely to withdraw from the study, which may underestimate the associations. A greater proportion of participants who did not participate in the COVID-19 study were older and had lower income, which may impact the validity of our findings.
Additionally, this study did not include individuals residing in long-term care institutions, who were more often hospitalized with COVID-19 and whose change in function or mobility associated with a COVID-19 diagnosis may be different than that experienced by community-dwelling older adults. In Canada, health measures taken by the governments and hospitals included creating additional critical care beds; in regions where hospitals were overwhelmed with COVID-19 admissions, some critical care patients were transferred to other hospital locations with increased capacity. 36 Thus, it is important to note that the low number of hospitalizations in our study is not a reflection that participants were turned away from hospitalization and sent home, but rather a reflection of the CLSA sample of community-dwelling middle aged and older adults.

Conclusions
In this population-based cohort study of community-dwelling middle-aged and older adults, we found that mild to moderate COVID-19 was associated with worsening mobility and difficulties in physical functioning. In view of the large number of adults diagnosed with COVID-19 worldwide, there is a need to further understand the longer-term impacts of the illness and to consider the development and implementation of effective intervention and management approaches to address any persistent deficits in mobility and functioning among those living in the community.