Diabetes (DM) and hypertension (HTN) are prevalent chronic diseases among older adults. For example, in the U.S., 1 in 4 older adults have DM, 3 in 4 have HTN and 1 in 6 have DM and HTN. Moreover, each year, health care costs attributable to DM and HTN are estimated at $327 billion and $131 billion USD respectively. Both diseases also impose tremendous burden on the health and well-being of older adults. For example, gait speed (GS) is reduced in older adults with DM or HTN compared to older adults without DM or HTN. Gait speed is a powerful indicator of health status among older adults. Reduced GS predicts various adverse health outcomes including falls, frailty, cognitive impairment, reduced quality of life, hospitalization and even death. Moreover, adequate GS is required to safely execute daily activities. For example, GS of 1.14 m/s or faster is required to safely cross the street. Reduced GS in older adults with DM or HTN can partly be explained by multimorbidity (e.g., older adults with DM are at increased risk of developing HTN) as well as complications that are frequently associated with DM and HTN. For example, older adults with DM or HTN are at increased risk of developing peripheral artery disease, which causes reduced lower extremity muscle strength and pain, as well as retinopathy, which causes vision impairment. Additionally, older adults with DM are at increased risk of developing peripheral neuropathy, which causes pain and impaired balance. Although the physiological mechanisms of these complications are largely understood, research is needed to determine the extent to which these complications contribute to GS decline among older adults with DM, HTN or DM and HTN.
The overarching objective of this thesis was to examine how multimorbidity patterns (i.e., types/combinations of chronic diseases), and sensory and motor impairments impact GS in older adults with DM, HTN or DM and HTN. This thesis also examined how GS changes over time (i.e., trajectories) in this population. This thesis is comprised of 3 manuscripts and was conducted using data from the National Health and Aging Trends Study (NHATS); a large, nationally representative sample of American older adults. Annual data collection began in 2011 and is ongoing. In 2015, the NHATS was replenished with approximately 50% new participants, to account for death and loss-to-follow-up. Therefore, data was analyzed in two cohorts: cohort A (individuals recruited in 2011) and cohort B (individuals recruited in 2015 and individuals recruited in 2011 who remained in the sample at the time of replenishment).
In manuscript 1, latent class analysis was performed to identify multimorbidity patterns in older adults with DM, HTN or DM and HTN. Additionally, analysis of covariance (ANCOVA) was conducted to examine differences in GS among these multimorbidity patterns. This study identified a total of nine multimorbidity patterns in cohort A: two patterns in older adults with DM (low multimorbidity and cardiovascular-joint multimorbidity), three patterns in older adults with HTN (low multimorbidity, psychological multimorbidity and cardiovascular multimorbidity) and four patterns in older adults with DM and HTN (metabolic-cardiovascular-psychological-joint multimorbidity, metabolic-bone-joint multimorbidity, metabolic-cardiovascular-joint multimorbidity and metabolic multimorbidity). Additionally, this study identified a total of ten multimorbidity patterns in cohort B: two patterns in older adults with DM (low multimorbidity and joint multimorbidity), four patterns in older adults with HTN (cardiovascular-joint-respiratory multimorbidity, cardiovascular multimorbidity, psychological-joint multimorbidity and joint multimorbidity) and four patterns in older adults with DM and HTN (metabolic-cardiovascular-joint-respiratory multimorbidity, metabolic-psychological-joint multimorbidity, metabolic-bone-joint multimorbidity and metabolic-joint multimorbidity). Overall, multimorbidity patterns with larger numbers of chronic diseases patterns or patterns that included depression or anxiety were associated with the slowest GS.
In manuscript 2, multinomial logistic regression was used to conduct state-based analyses which examined the relationship between impairments (i.e., hearing, and vision impairment, pain, balance, and lower extremity strength impairment) and GS transitions (i.e., fast to, intermediate walker, intermediate to slow walker etc.) in older adults with DM, HTN or DM and HTN. Balance and lower extremity strength impairment were associated with an increased risk of GS decline (i.e., transitioning from an intermediate to slow walker). Moreover, older adults with vision, hearing, balance, or lower extremity strength impairment and those who used pain medication at least 5 days/week were more likely to be slow walkers at baseline and remain slow walkers at follow-up.
In manuscript 3, group-based trajectory modeling was used to identify longitudinal trajectories of GS in older adults with DM, HTN or DM and HTN. Multinomial logistic regression was then conducted to examine the correlates of these trajectories. This study identified four GS trajectories in both cohorts: i) fast-stable GS, ii) intermediate GS with slow decline, iii) intermediate GS with moderate decline and iv) slow GS with fast decline. Additionally, one trajectory was unique to cohort A: intermediate-stable GS and two trajectories were unique to cohort B: fast GS with slow decline, and intermediate GS with fast decline. In both cohorts, individuals who were older, Black (non-Hispanic), had a higher number of chronic diseases or higher body mass index (BMI) were more likely to belong to a trajectory group with faster GS decline. Conversely, individuals with higher education, or higher baseline GS were less likely to belong to a trajectory group with faster GS decline.
From a population health perspective, findings from this thesis can inform large-scale monitoring and management strategies to mitigate GS decline in older adults with DM, HTN or DM and HTN. For example, individuals who are older, identify as Black non-Hispanic or those with a higher number of chronic diseases or higher BMI may benefit from more frequent monitoring of their GS. Moreover, findings from this thesis can be used to determine how older adults with different multimorbidity patterns, or different types of sensory and motor impairments respond to interventions. Lastly, older adults with DM and/or HTN should be educated about the importance of maintaining their GS as they age to prevent adverse outcomes including falls, hospitalization, and premature death. / Thesis / Doctor of Philosophy (PhD) / Diabetes and hypertension are common chronic diseases among older adults globally. Moreover, these two chronic diseases are frequently found in the same individual due to shared risk factors including physical inactivity, and family history. Additionally, older adults with diabetes and/or hypertension are at risk of developing complications including vision loss, heart disease and stroke. These complications often cause impairments (i.e., changes in body structure or function) which also occur with aging including vision and hearing impairment, pain, and balance impairment which may reduce physical function (e.g., walking speed). There is a need for research to examine which other chronic diseases are linked to diabetes and hypertension and the impact of these diseases and disease-related impairments on walking speed among older adults with diabetes and/or hypertension. Moreover, it is important to examine how walking speed changes over time (i.e., trajectories) in older adults with diabetes and/or hypertension. Results from this thesis show that older adults with diabetes and/or hypertension who used pain medication at least 5 days/week, had vision, balance, or lower extremity strength impairment as well as older adults who are female, Black non-Hispanic, had a higher number of chronic diseases and a higher body mass index were at greatest risk of reduced walking speed. On the other hand, higher education and higher baseline walking speed were linked to lower risk of walking speed decline. Older adults who were identified as “high-risk” may benefit from closer monitoring and management of their walking speed to prevent further decline.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/28824 |
| Date | January 2023 |
| Creators | Gravesande, Janelle |
| Contributors | Richardson, Julie, Ma, Jinhui, Griffith, Lauren, Tang, Ada, Rehabilitation Science |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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