Analysis of patient self-completing (RUDAS) data
Data was collected from 933 individuals (549 male) aged 60 years and over from three regions of Nepal: Humla (mountainous region); Kavrepalachowk (hilly region) and Siraha (low-lying region). The sample is summarised in Table 1 below.
Table 1: descriptive summary of sample (RUDAS/patient self-completers)
Variable
|
Frequency (valid %)
|
Region
Mountainous
Hilly
Low-lying
|
367 (39.3%)
238 (25.5%)
328 (35.2%)
|
Sex
Female
Male
|
384 (41.2%)
549 (58.8%)
|
Age group
60-64 years
65-69 years
70-74 years
75+ years
|
298 (31.9%)
241 (25.8%)
204 (21.9%)
190 (20.4%)
|
Under the assumption that prevalence of cognitive impairment was diagnosed by a score of 22 or less in the RUDAS test, 501 participants (53.7%) were classified as having cognitive impairment (95% confidence interval 50.5% to 56.9%).
Slightly higher prevalences of cognitive impairment were revealed in females than males. Prevalence of cognitive impairment by gender, with associated 95% confidence intervals (CIs), is summarised in Table 2 and Figure 1.
Table 2: prevalence of cognitive impairment and associated 95% CIs, by gender
Gender
|
Prevalence
|
95% CI for prevalence
|
Males
|
248/549; 51.7%
|
(47.6%, 55.9%)
|
Females
|
217/385; 56.5%
|
(51.6%, 61.5%)
|
The gender effect was not statistically significant at the 5% significance level (χ2(1)=2.08; p=0.150).
A strong age effect was observed, with prevalence of cognitive impairment increasing monotonically in age. Prevalence of cognitive impairment by age group, with associated 95% confidence intervals (CIs), is summarised in Table 3 and Figure 2.
Table 3: prevalence of cognitive impairment and associated 95% CIs, by age group
Age group
|
Prevalence
|
95% CI for prevalence
|
60-64 years
|
131/298; 44.0%
|
(38.3%, 49.6%)
|
65-69 years
|
110/241; 45.6%
|
(39.3%, 51.9%)
|
70-74 years
|
126/204; 61.8%
|
(55.1%, 68.4%)
|
75+ years
|
134/190; 70.5%
|
(64.0%, 77.0%)
|
The age effect was significant (χ2(3)=44.6; p<0.001) and large in effect (φ=0.219).
A strong geographic effect was also observed, with prevalence of cognitive impairment increasing with higher altitudes. Prevalence of cognitive impairment by region is summarised in Table 4 and Figure 3.
Table 4: prevalence of cognitive impairment and associated 95% CIs, by region
Region
|
Prevalence
|
95% CI for prevalence
|
Kavrepalanchowk (hilly)
|
110/238; 46.2%
|
(39.9%, 52.6%)
|
Humla (mountainous)
|
247/361; 67.3%
|
(62.5%, 72.1%)
|
Tarai (low-lying)
|
75/328; 22.9%
|
(18.3%, 27.4%)
|
The geographic effect was significant (χ2(2)=137.6; p<0.001) and very large in effect (φ=0.384).
A multiple logistic regression conducted on the data revealed that in a controlled model, compared to the reference category of age 50-64 years; all age groups were significantly associated with the prevalence of cognitive impairment (p=0.043 for age 65-69, p<0.001 for other age groups); compared to the reference category of low-lying region, both hilly and mountainous regions were significantly associated with the prevalence of cognitive impairment (p<0.001 in all cases); and sex was significantly associated with cognitive impairment (p<0.001). Model parameters are summarised in Table 5.
Table 5: logistic regression parameters (RUDAS/patient self-completers)
Variable
|
p-value
|
Odds ratio
|
95% CI for OR
|
Sex
Female (reference)
Male
|
<0.001
|
1.83
|
(1.34, 2.49)
|
Age group
60-64 years (reference)
65-69 years
70-74 years
75+ years
|
0.043
<0.001
<0.001
|
1.49
3.17
6.41
|
(1.01, 2.19)
(2.07, 4.83)
(4.05, 10.2)
|
Region
Low-lying (reference)
Hilly
Mountainous
|
<0.001
<0.001
|
3.13
11.8
|
(2.13, 4.61)
(7.97, 17.6)
|
Analysis of carers’ data (Memory First Aid Informant Questionnaire/CSI-D for informant)
Data was collected from carers of 219 older people (102 male) aged 60 years and over from the same three regions of Nepal utilised in the collection of data directly from older people.
The sample is summarised in Table 6 below.
Table 6: descriptive summary of sample (Memory First Aid Informant Questionnaire/CSI-D- for informant /carer completion)
Variable
|
Frequency (valid %)
|
Region
Mountainous
Hilly
Low-lying
|
22 (10.0%)
136 (62.1%)
61 (27.9%)
|
Sex
Female
Male
|
117 (53.4%)
102 (46.6%)
|
Age group
60-64 years
65-69 years
70-74 years
75+ years
|
32 (14.6%)
50 (22.8%)
67 (30.6%)
70 (32.0%)
|
Under the assumption that prevalence of cognitive impairment was diagnosed by a score of 6 or more in the CSID for informant test, 155 participants (70.8%) were classified as having cognitive impairment (95% confidence interval 64.8% to 76.8%).
Slightly higher prevalences were revealed in males than females. Prevalence of cognitive impairment in males and females is summarised in Table 7 and Figure 4.
Table 7: cognitive impairment by gender (CSI-D for informant/carer completion)
Gender
|
Prevalence
|
95% CI for prevalence
|
Males
|
78/102; 76.5%
|
(70.9%, 82.1%)
|
Females
|
77/117; 65.8%
|
(59.5%, 72.1%)
|
The gender effect was not statistically significant at the 5% significance level (χ2(1)=2.99; p=0.084).
A strong age effect was observed, with prevalence of cognitive impairment increasing monotonically in age. Prevalence of cognitive impairment by age group, with associated 95% CIs, is summarised in Table 8 and Figure 5.
Table 8: prevalence of cognitive impairment and associated 95% CIs, by age group
Age group
|
Prevalence
|
95% CI for prevalence
|
60-64 years
|
8/32; 25.0%
|
(19.3%, 30.7%)
|
65-69 years
|
32/50; 64.0%
|
(57.6%, 70.4%)
|
70-74 years
|
52/67; 77.6%
|
(72.1%, 83.1%)
|
75+ years
|
63/70; 90.0%
|
(86.0%, 94.0%)
|
The age effect was significant (χ2(3)=47.6; p<0.001) and very large in effect (φ=0.466). The main effect can be seen to be a step change in prevalence between the youngest and second-youngest age groups (Figure 3).
A strong geographic effect was observed, with prevalence of cognitive impairment increasing with higher altitudes. Prevalence of cognitive impairment by geographical region is summarised in Table 9 and Figure 6.
Table 9: prevalence of cognitive impairment and associated 95% CIs, by region
Region
|
Prevalence
|
95% CI for prevalence
|
Kavrepalanchowk (hilly)
|
114/136; 83.8%
|
(78.9%, 88.7%)
|
Humla (mountainous)
|
19/22; 86.4%
|
(81.8%, 90.9%)
|
Tarai (low-lying)
|
22/61; 36.1%
|
(29.7%, 42.4%)
|
The geographic effect was significant (χ2(2)=49.3; p<0.001) and very large in effect (φ=0.475).
A multiple logistic regression conducted on the data revealed that in a controlled model, compared to the reference category of age 50-64 years; all age groups were significantly associated with the prevalence of cognitive impairment (p=0.020 for age 65-69, p<0.001 for other age groups); compared to the reference category of low-lying region, both hilly and mountainous regions were significantly associated with the prevalence of cognitive impairment (p<0.001 in all cases). Sex was not significantly associated with CSI (p=0.721). Model parameters are summarised in Table 3.
Table 10: logistic regression parameters (Memory First Aid Informant Questionnaire/CSI-D for informant/carer completers)
Variable
|
p-value
|
Odds ratio
|
95% CI for OR
|
Sex
Female (reference)
Male
|
0.721
|
1.15
|
(0.536, 2.46)
|
Age group
60-64 years (reference)
65-69 years
70-74 years
75+ years
|
0.020
<0.001
<0.001
|
3.72
7.65
23.6
|
(1.23, 11.3)
(2.49, 23.5)
(6.73, 82.7)
|
Region
Low-lying (reference)
Hilly
Mountainous
|
<0.001
<0.001
|
8.37
11.5
|
(3.81, 18.4)
(2.56, 51.4)
|