In the analytical sample of Study IV, including 3,241 participants with valid baseline measurements of walking speed, the mean age was 74.3 ± 11.0 years, and 64.4% were females. One third of baseline participants reported a walking speed of <0.8 m/s. By the three-year follow-up, 411 participants (12%) were deceased: 174 (5%) from cardiovascular causes and 237 (7%) from other causes. A further 682 (21%) individuals died by the time of the five-year follow-up: 287 (9%) of cardiovascular and 395 (12%) of other causes. According to the findings in table 3, a greater cardiovascular burden was associated with an elevated three-year mortality risk only in the presence of slow walking speed (reference group: preserved walking speed and no cardiovascular disease). The pattern of results was similar for five-year mortality, although this time, even in the presence of preserved walking speed, having one or two cardiovascular conditions was associated with greater risk of death. An increasing burden of neuropsychiatric disease was associated with greater three-year mortality among individuals with slow walking speed, relative to participants with intact walking speed and no neuropsychiatric disease (table 3). When looking only at individuals with slow walking speeds, the crude excess risk of three-year mortality was 18.4/100 person-years in those with two or more cardiovascular diseases and 17/100 in those with two or more neuropsychiatric diseases (reference: intact walking speed). While some minor attenuation of results was observed for the five-year follow-up, the pattern remained consistent. Quantifying the joint effect of multimorbidity and walking speed on mortality using additive interaction revealed that 42% and 34% of the relative excess risk of death was attributable to the effect of slow walking speed and cardiovascular and neuropsychiatric multimorbidity, respectively.
Table 3. Association between cardiovascular and neuropsychiatric multimorbidity by walking speed.
WS = walking speed; IR = incident rate; HR = hazard ratio; CI = confidence interval
4.5 PROGNOSTIC ROLE OF WALKING SPEED (STUDY IV)
In the analytical sample of Study IV, including 3,241 participants with valid baseline measurements of walking speed, the mean age was 74.3 ± 11.0 years, and 64.4% were females. One third of baseline participants reported a walking speed of <0.8 m/s. By the three-year follow-up, 411 participants (12%) were deceased: 174 (5%) from cardiovascular causes and 237 (7%) from other causes. A further 682 (21%) individuals died by the time of the five-year follow-up: 287 (9%) of cardiovascular and 395 (12%) of other causes. According to the findings in table 3, a greater cardiovascular burden was associated with an elevated three-year mortality risk only in the presence of slow walking speed (reference group: preserved walking speed and no cardiovascular disease). The pattern of results was similar for five-year mortality, although this time, even in the presence of preserved walking speed, having one or two cardiovascular conditions was associated with greater risk of death. An increasing burden of neuropsychiatric disease was associated with greater three-year mortality among individuals with slow walking speed, relative to participants with intact walking speed and no neuropsychiatric disease (table 3). When looking only at individuals with slow walking speeds, the crude excess risk of three-year mortality was 18.4/100 person-years in those with two or more cardiovascular diseases and 17/100 in those with two or more neuropsychiatric diseases (reference: intact walking speed). While some minor attenuation of results was observed for the five-year follow-up, the pattern remained consistent. Quantifying the joint effect of multimorbidity and walking speed on mortality using additive interaction revealed that 42% and 34% of the relative excess risk of death was attributable to the effect of slow walking speed and cardiovascular and neuropsychiatric multimorbidity, respectively.
Table 3. Association between cardiovascular and neuropsychiatric multimorbidity by walking speed.
Figure 1 shows the hazard ratios (HRs) for three-year all-cause mortality across walking speed
(continuous variable), depending on the number of cardiovascular and neuropsychiatric diseases. Participants with a speed of <0.8 m/s had a higher mortality (dashed line). Mortality was exacerbated in the presence of one or more cardiovascular or neuropsychiatric diseases. Individuals with two or more neuropsychiatric diseases did not differ in mortality risk from those with one neuropsychiatric disease. The pattern of results was unchanged at five years. Focusing exclusively on individuals who died of cardiovascular causes, cardiovascular diseases were associated with a greater relative risk of three-year mortality, irrespective of walking speed. Examining those who died of causes other than cardiovascular disease revealed that a higher burden of cardiovascular diseases was associated with a greater change in three-year mortality only in individuals with slow walking speeds. These findings remained consistent after a five-year mortality follow-up, as well as in the analysis of neuropsychiatric conditions. An alternative cutoff of <1 m/s to define slow walking speed did not affect the pattern of the associations presented.
Figure 11. Estimated hazard ratio (HRs) of 3-year all-cause mortality for different values of walking
speed (reference 0.8 m/s) in the overall population (centering the number of diseases on their average number) and in participants with 0, 1, or 2+ cardiovascular and neuropsychiatric diseases.
Cox regression models adjusted for age, sex, education, number of NP diseases or CV diseases, number of medications, malnutrition, institutionalization, and Mini-Mental State Examination score.
Figure 1 shows the hazard ratios (HRs) for three-year all-cause mortality across walking speed
(continuous variable), depending on the number of cardiovascular and neuropsychiatric diseases. Participants with a speed of <0.8 m/s had a higher mortality (dashed line). Mortality was exacerbated in the presence of one or more cardiovascular or neuropsychiatric diseases. Individuals with two or more neuropsychiatric diseases did not differ in mortality risk from those with one neuropsychiatric disease. The pattern of results was unchanged at five years. Focusing exclusively on individuals who died of cardiovascular causes, cardiovascular diseases were associated with a greater relative risk of three-year mortality, irrespective of walking speed. Examining those who died of causes other than cardiovascular disease revealed that a higher burden of cardiovascular diseases was associated with a greater change in three-year mortality only in individuals with slow walking speeds. These findings remained consistent after a five-year mortality follow-up, as well as in the analysis of neuropsychiatric conditions. An alternative cutoff of <1 m/s to define slow walking speed did not affect the pattern of the associations presented.
Figure 11. Estimated hazard ratio (HRs) of 3-year all-cause mortality for different values of walking
speed (reference 0.8 m/s) in the overall population (centering the number of diseases on their average number) and in participants with 0, 1, or 2+ cardiovascular and neuropsychiatric diseases.
Cox regression models adjusted for age, sex, education, number of NP diseases or CV diseases, number of medications, malnutrition, institutionalization, and Mini-Mental State Examination score.