1. Baseline characteristics
Table 1 presents the baseline characteristics of the study sample. Overall, the present study included 13,413 individuals with 5,639 urban residents and 7,774 rural residents. First, results suggested that relative to rural areas, urban areas had a higher proportion of individuals living with paved roads (P < 0.001). Specifically, 59.09% of the rural residents lived with paved roads, and the figure surged to 74.00% among urban residents. In addition, a higher proportion of urban residents (41.66%) lived with a groundwater system, in comparison to their rural counterparts (20.18%, P < 0.001). Last, individual-level attributes, including household income, BMI, and physical activity, varied across urban and rural areas.
Table 1 Baseline characteristics of study sample, stratified by urban vs rural settings, n (%)
Characteristic
|
Total
(N = 13413)
|
Urban
(N = 5639)
|
Rural
(N = 7774)
|
P value
|
Road type
|
|
|
|
|
|
|
|
unpaved roads
|
3104 (23.14)
|
1001 (17.75)
|
2103 (27.05)
|
<0.0001
|
paved roads
|
8767 (65.36)
|
4173 (74.00)
|
4594 (59.09)
|
others
|
1541 (11.50)
|
465 (8.54)
|
1077 (13.85)
|
Primary care institutions
|
|
|
|
|
|
|
0.07
|
0
|
3226 (24.05)
|
1333 (23.64)
|
1893 (24.35)
|
1
|
5188 (38.68)
|
2210 (39.19)
|
2978 (38.31)
|
2
|
3098 (23.10)
|
1339 (23.75)
|
1759 (22.63)
|
≥3
|
1901 (14.17)
|
757 (13.42)
|
1144 (14.72)
|
Groundwater system
|
|
|
|
|
|
|
<0.0001
|
no
|
9495 (70.79)
|
3290 (58.34)
|
6205 (79.82)
|
yes
|
3918 (29.21)
|
2349 (41.66)
|
1569 (20.18)
|
Sex
|
|
|
|
|
|
|
0.13
|
men
|
6431 (47.95)
|
2660 (47.17)
|
3771 (48.51)
|
women
|
6982 (52.05)
|
2979 (52.83)
|
4003 (51.49)
|
Age, years #
|
59.09 (±10.16)
|
58.91 (±10.14)
|
(59.21 (±10.18)
|
<0.0001
|
Marital status
|
|
|
|
|
|
|
0.08
|
married
|
10741 (80.08)
|
4475 (79.36)
|
6266 (80.60)
|
other
|
2672 (19.92)
|
1164 (20.64)
|
1508 (19.40)
|
Education attainment
|
|
|
|
|
|
|
0.67
|
illiteracy
|
3672 (27.38)
|
1543 (27.36)
|
2129 (27.39)
|
some primary school
|
2371 (17.68)
|
1019 (18.07)
|
1352 (17.39)
|
primary school
|
2895 (21.58)
|
1195 (21.19)
|
1700 (21.87)
|
junior school or above
|
4475 (33.36)
|
1882 (33.37)
|
2593 (33.35)
|
Household income (quartile)
|
<0.0001
|
1st (the poorest)
|
3218 (23.99)
|
1477 (26.19)
|
1741 (22.40)
|
2nd
|
3466 (25.84)
|
1363 (24.17)
|
2103 (27.05)
|
3rd
|
3345 (24.94)
|
1418 (25.15)
|
1927 (24.79)
|
4th (the richest)
|
3384 (25.23)
|
1381 (24.49)
|
2003 (25.77)
|
BMI (kg/m2)
|
|
|
|
|
|
|
<0.001
|
<18.5
|
935 (6.97)
|
358 (6.35)
|
577 (7.42)
|
≥18.5 and <25
|
8362 (62.34)
|
3449 (61.16)
|
4913 (63.20)
|
≥25 and <30 (overweight)
|
3462 (25.81)
|
1532 (27.17)
|
1930 (24.83)
|
≥30 (obese)
|
654 (4.88)
|
300 (5.32)
|
354 (4.55)
|
Health care insurance
|
|
|
|
|
|
|
0.14
|
uninsured
|
893 (6.66)
|
375 (6.65)
|
518 (6.66)
|
RCMI
|
9771 (72.85)
|
4063 (72.05)
|
570 (73.42)
|
others
|
2749 (20.50)
|
1201 (21.30)
|
1548 (19.91)
|
Physical activity
|
|
|
|
|
|
|
<0.0001
|
never
|
12686 (94.58)
|
5144 (91.22)
|
7542 (97.02)
|
seldom
|
112 (0.84)
|
75 (1.33)
|
37 (0.48)
|
a weekly basis
|
129 (0.96)
|
88 (1.56)
|
41 (0.53)
|
a daily basis
|
486 (3.62)
|
332 (5.89)
|
154 (1.98)
|
# mean (± standard deviation)
|
2. Prevalence of multimorbidity and the fourteen NCDs
According to weighted analyses in Table 2, over 65% of study subjects had at least one NCDs, followed by 19.11% with two NCDs, 9.81% with three NCDs, and around 10% with at least 4 NCDs. The top three NCDs were arthritis or rheumatism (33.08%), hypertension (24.54%), and digestive disease (21.98%). In contrast, cancer, memory-related disease, and mental problems were the least prevalent NCDs. There were 0.90%, 1.45%, and 1.78% of the subjects self-reporting to have cancer, memory-related disease, and mental problems, respectively. Furthermore, urban subjects were more likely to have hypertension, heart problems, dyslipidemia, and diabetes, whereas rural subjects had a greater probability of asthma (P < 0.05). After controlling for CHARLS sampling weights, there existed no urban-rural disparities in the prevalence of each NCD since the 95% CI of urban residents overlapped with that of rural residents across all NCDs.
Table 2 Weighted and unweighted estimation of the prevalence of multimorbidity and fourteen NCDs by urban vs. rural areas in 2011
Characteristics
|
Unweighted sample, n (%)
|
Weighted to reflect to China's population, % (95 CI)
|
All (N =13,413)
|
Urban (N = 5,639)
|
Rural (N=7,774)
|
All
|
Urban
|
Rural
|
Chronic disease
|
|
|
|
|
|
|
0
|
4216 (31.43)
|
1730 (30.68)
|
2486 (31.98)
|
32.09
|
(28.97- 34.11)
|
32.61
|
(30.62 - 34.67)
|
31.48
|
(30.50 - 33.72)
|
1
|
4020 (29.97)
|
1665 (29.53)
|
2355 (30.29)
|
30.58
|
(28.73- 32.57)
|
30.55
|
(29.25 - 31.89)
|
30.62
|
(29.46 - 31.73)
|
2
|
2648 (19.74)
|
1146 (20.32)
|
1502 (19.32)
|
19.11
|
(17.89 - 21.28)
|
18.75
|
(17.65 - 19.90)
|
19.53
|
(18.14 - 20.12)
|
3
|
1393 (10.39)
|
586 (10.39)
|
807 (10.38)
|
9.81
|
(8.58 - 10.62)
|
10.04
|
(9.19 - 10.95)
|
9.55
|
(9.16 - 10.50)
|
4
|
680 (5.07)
|
310 (5.5)
|
370 (4.76)
|
4.82
|
(4.17 - 6.07)
|
4.64
|
(4.08 - 5.28)
|
5.04
|
(4.31 - 5.39)
|
5
|
304 (2.27)
|
131 (2.32)
|
173 (2.23)
|
2.25
|
(1.61 - 2.72)
|
2.39
|
(1.95 - 2.92)
|
2.10
|
(1.92 - 2.65)
|
6
|
97 (0.72)
|
46 (0.82)
|
51 (0.66)
|
0.93
|
(0.69 - 2.25)
|
0.65
|
(0.47 - 0.91)
|
1.25
|
(0.62 - 1.38)
|
7
|
37 (0.28)
|
17 (0.3)
|
20 (0.26)
|
0.27
|
(0.17 - 0.54)
|
0.24
|
(0.14 - 0.42)
|
0.31
|
(0.18 - 0.40)
|
8
|
12 (0.09)
|
5 (0.09)
|
7 (0.09)
|
0.09
|
(0.03 - 0.21)
|
0.09
|
(0.04 - 0.22)
|
0.08
|
(0.05 - 0.16)
|
9
|
4 (0.03)
|
2 (0.04)
|
2 (0.03)
|
0.03
|
(0.01 - 0.12)
|
0.03
|
(0.01 - 0.12)
|
0.03
|
(0.01 - 0.08)
|
10
|
2 (0.01)
|
1 (0.02)
|
1 (0.01)
|
0.02
|
(0.00 - 0.16)
|
0.01
|
(0.00 - 0.08)
|
0.02
|
(0.00 - 0.07)
|
arthritis or rheumatism
|
4570 (34.07)
|
1923 (34.1)
|
2647 (34.05)
|
33.08
|
(31.29 - 34.93)
|
32.87
|
(30.59 - 35.24)
|
33.33
|
(30.53 - 36.25)
|
hypertension
|
3276 (24.42)
|
1453 (25.77)
|
1823 (23.45)
|
24.54
|
(22.85 - 26.31)
|
23.69
|
(21.91 - 25.58)
|
25.53
|
(22.55 - 28.75)
|
digestive disease
|
3083 (22.99)
|
1251 (22.18)
|
1832 (23.57)
|
21.98
|
(20.68 - 23.33)
|
22.69
|
(21.24 - 24.21)
|
21.15
|
(18.92 - 23.56)
|
heart problems
|
1538 (11.47)
|
728 (12.91)
|
810 (10.42)
|
11.21
|
(10.23 - 12.27)
|
10.18
|
(9.05 - 11.45)
|
12.41
|
(10.79 - 14.23)
|
chronic lung diseases
|
1616 (12.05)
|
688 (12.2)
|
928 (11.94)
|
11.82
|
(10.99 - 12.71)
|
11.89
|
(10.84 - 13.03)
|
11.74
|
(10.45 - 13.18)
|
dyslipidemia
|
1162 (8.66)
|
535 (9.49)
|
627 (8.07)
|
8.86
|
(7.99 - 9.81)
|
8.21
|
(7.12 - 9.45)
|
9.62
|
(8.28 -11.14)
|
chronic kidney disease
|
833 (6.21)
|
324 (5.75)
|
509 (6.55)
|
5.96
|
(5.34 - 6.64)
|
6.48
|
(5.58 - 7.52)
|
5.35
|
(4.57 - 6.25)
|
diabetes
|
743 (5.54)
|
356 (6.31)
|
387 (4.98)
|
5.85
|
(5.24 - 6.52)
|
5.14
|
(4.45 - 5.93)
|
6.67
|
(5.67 - 7.83)
|
Chronic liver disease
|
521 (3.88)
|
224 (3.97)
|
297 (3.82)
|
3.90
|
(3.44 - 4.43)
|
3.79
|
(3.23 - 4.45)
|
4.03
|
(3.32 - 4.90)
|
asthma
|
511 (3.81)
|
206 (3.65)
|
305 (3.92)
|
3.69
|
(3.26 - 4.17)
|
3.97
|
(3.41 - 4.62)
|
3.36
|
(2.75 - 4.11)
|
stroke
|
407 (3.03)
|
197 (3.49)
|
210 (2.7)
|
2.17
|
(1.83 - 2.57)
|
2.00
|
(1.58 - 2.52)
|
2.37
|
(1.84 - 3.03)
|
mental problems
|
258 (1.92)
|
111 (1.97)
|
147 (1.89)
|
1.78
|
(1.48 - 2.14)
|
1.79
|
(1.40 - 2.28)
|
1.77
|
(1.34 - 2.34)
|
memory-related disease
|
177 (1.32)
|
84 (1.49)
|
93 (1.2)
|
1.45
|
(1.16 - 1.80)
|
1.43
|
(1.08 - 1.89)
|
1.47
|
(1.03 - 2.08)
|
cancer
|
132 (0.98)
|
51 (0.9)
|
81 (1.04)
|
0.90
|
(0.74 - 1.09)
|
1.03
|
(0.82 - 1.30)
|
0.74
|
(0.52 - 1.04)
|
Note: CI, confident interval.
3. H1 Urban vs. rural disparities
Table 3 presents results from negative binomial analyses. Results suggested that urban residents had a higher probability of more NCDs after controlling for all other covariates (Model 1 in Table 3, IRR = 1.05, 95% CI, 1.01 - 1.09). Results from Model 2, however, suggested that there existed no urban-rural disparities in the number of NCDs (IRR = 1.02, 95% CI, 0.95 - 1.02) after taking neighborhood-level variations into account. Results pertaining to urban vs. rural disparities in Model 2 were in line with those from subgroup analyses in Table 4.
Table 3 Negative binomial regression analyses of multimorbidity, IRR (95% CI)
Characteristics
|
Univariate analysis
|
Model 1
|
Model 2†
|
Road type
|
|
|
|
|
|
|
unpaved roads
|
1.00
|
1.00
|
1.00
|
paved roads
|
0.88
|
(0.85 - 0.92) ***
|
0.87
|
(0.83 - 0.91) ***
|
0.86
|
(0.78 - 0.95) ***
|
others
|
0.93
|
(0.87 - 0.98) ***
|
0.93
|
(0.87 - 0.99) **
|
0.90
|
(0.79 - 1.03)
|
Urban (vs. rural)
|
1.04
|
(1.01 - 1.08) *
|
1.05
|
(1.01 - 1.09) **
|
1.02
|
(0.95 - 1.10)
|
Primary care institutions
|
|
|
|
|
0
|
1.00
|
1.00
|
1.00
|
1
|
0.99
|
(0.95 - 1.03)
|
0.99
|
(0.95 - 1.03)
|
1.01
|
(0.92 - 1.11)
|
2
|
0.99
|
(0.94 - 1.04)
|
1.00
|
(0.95 - 1.05)
|
1.02
|
(0.92 - 1.13)
|
≥3
|
0.90
|
(0.85 - 0.96) **
|
0.94
|
(0.89 - 0.99) *
|
0.94
|
(0.83 - 1.06)
|
Groundwater system (yes vs. no)
|
1.00
|
(0.96 - 1.04)
|
1.00
|
(0.96 - 1.05)
|
1.02
|
(0.94 - 1.11)
|
Age
|
1.00
|
(0.98 - 1.01)
|
1.00
|
(1.00 - 1.00)
|
1.00
|
(1.00 - 1.00)
|
Women (vs. men)
|
1.00
|
(0.96 - 1.03)
|
1.00
|
(0.96 - 1.04)
|
0.99
|
(0.96 - 1.03)
|
Married (vs. others)
|
0.97
|
(0.93 - 1.02)
|
0.97
|
(0.93 - 1.01)
|
0.97
|
(0.93 - 1.02)
|
Household income
|
|
|
|
|
|
1st (the poorest)
|
1.00
|
1.00
|
1.00
|
2nd
|
1.03
|
(0.98 - 1.07)
|
1.03
|
(0.98 - 1.08)
|
0.99
|
(0.95 - 1.04)
|
3rd
|
0.96
|
(0.91 - 1.00)
|
0.95
|
(0.93 - 1.00)
|
0.94
|
(0.89 - 0.99) *
|
4th (the richest)
|
0.94
|
(0.89 - 0.99) *
|
0.93
|
(0.89 - 0.98) **
|
0.93
|
(0.88 - 0.98) *
|
Education attainment
|
|
|
|
|
|
illiteracy
|
1.00
|
1.00
|
1.00
|
some primary school
|
1.03
|
(0.97 - 1.08)
|
1.03
|
(0.97 - 1.08)
|
1.03
|
(0.98 - 1.08)
|
primary school
|
1.01
|
(0.96 - 1.06)
|
1.01
|
(0.96 - 1.06)
|
1.00
|
(0.95 - 1.06)
|
junior school or above
|
1.03
|
(0.99 - 1.07)
|
1.03
|
(0.98 - 1.08)
|
1.02
|
(0.97 - 1.08)
|
Health care insurance
|
|
|
|
|
|
uninsured
|
1.00
|
1.00
|
1.00
|
RCMI
|
1.03
|
(0.96 - 1.10)
|
1.03
|
(0.96 - 1.11)
|
1.04
|
(0.97 - 1.11)
|
others
|
1.04
|
(0.96 - 1.12)
|
1.06
|
(0.98 - 1.15)
|
1.07
|
(0.99 - 1.15)
|
BMI
|
|
|
|
|
|
<18.5
|
1.00
|
1.00
|
1.00
|
≥18.5 and <25
|
0.91
|
(0.85 - 0.97) *
|
0.91
|
(0.85 - 0.97) **
|
0.90
|
(0.84 - 0.96) **
|
≥25 and <30
|
1.15
|
(1.08 - 1.24) ***
|
1.16
|
(1.08 - 1.25) ***
|
1.14
|
(1.06 - 1.22) ***
|
≥30
|
1.36
|
(1.24 - 1.50) ***
|
1.37
|
(1.24 - 1.50) ***
|
1.33
|
(1.21 - 1.46) ***
|
Physical activity
|
|
|
|
|
|
|
never
|
1.00
|
1.00
|
1.00
|
seldom
|
1.00
|
(0.83 - 1.21)
|
1.00
|
(0.83 - 1.20)
|
0.96
|
(0.80 - 1.15)
|
a weekly basis
|
1.09
|
(0.92 - 1.29)
|
1.09
|
(0.92 - 1.29)
|
1.06
|
(0.90 - 1.25)
|
a daily basis
|
1.10
|
(1.01 - 1.20) *
|
1.08
|
(0.99 - 1.18)
|
1.08
|
(0.98 - 1.18)
|
Note: *** P < 0.001; ** P < 0.01; * P < 0.05.
† standard error was adjusted for clusters within neighborhoods
IRR, incident rate ratio.
CI, confident interval.
Table 4 Subgroup logistic regression analyses of the fourteen chronic diseases, OR (95%CI)
characteristics
|
hypertension
|
dyslipidemia
|
diabetes
|
chronic lung disease
|
cancer
|
chronic liver disease
|
heart problems
|
unpaved roads
|
1.00
|
1.00
|
1.00
|
1.00
|
1.00
|
1.00
|
1.00
|
paved roads
|
1.00 (0.85 - 1.18)
|
1.13 (0.86 - 1.49)
|
1.05 (0.83 - 1.33)
|
0.76 (0.63 - 0.93)**
|
0.91 (0.58 - 1.43)
|
0.74 (0.55 - 0.99)*
|
0.86 (0.66 - 1.11)
|
others
|
1.06 (0.84 - 1.33)
|
0.75 (0.50 - 1.12)
|
0.90 (0.64 - 1.27)
|
0.93 (0.71 - 1.21)
|
0.80 (0.41 - 1.55)
|
0.87 (0.58 - 1.32)
|
1.09 (0.76 - 1.56)
|
urban (vs. rural)
|
1.05 (0.92 - 1.19)
|
0.95 (0.77 - 1.17)
|
1.03 (0.86 - 1.23)
|
1.09 (0.93 - 1.27)
|
0.80 (0.55 - 1.16)
|
1.02 (0.80 - 1.29)
|
1.13 (0.93 - 1.38)
|
characteristics
|
stroke
|
chronic kidney disease
|
digestive disease
|
mental problems
|
memory disease
|
arthritis or rheumatism
|
asthma
|
unpaved roads
|
1.00
|
1.00
|
1.00
|
1.00
|
1.00
|
1.00
|
1.00
|
paved roads
|
1.12 (0.74 - 1.69)
|
0.68 (0.51 - 0.89)**
|
0.82 (0.69 - 0.97)*
|
0.67 (0.43 - 1.07)
|
0.62 (0.38 - 1.01)
|
0.69 (0.55 - 0.87)**
|
0.67 (0.51 - 0.88)***
|
others
|
0.86 (0.47 - 1.57)
|
0.79 (0.53 - 1.16)
|
0.79 (0.63 - 1.01)
|
0.79 (0.41 - 1.51)
|
0.46 (0.21 - 1.00)
|
0.90 (0.65 - 1.23)
|
0.66 (0.44 - 0.98)*
|
urban (vs. rural)
|
1.09 (0.80 -1.49)
|
0.89 (0.71 - 1.12)
|
0.96 (0.84 - 1.10)
|
1.26 (0.86 - 1.84)
|
1.13 (0.76 - 1.68)
|
1.05 (0.88 - 1.26)
|
0.97 (0.77 - 1.23)
|
Note: *** P < 0.001; ** P < 0.01; * P < 0.05.
4. H2 Neighborhood's road types
Results in Table 3 suggest that living with paved roads was associated with fewer NCDs, in comparison with those living with unpaved roads. Specifically, after controlling for all covariates in Model 1, subjects living with paved roads (IRR = 0.87, 95% CI, 0.83 - 0.91) had a significantly lower incidence rate of more NCDs relative to those living with unpaved roads. Results here were consistent after controlling for neighborhood-level variations in Model 2. Subgroup analyses in Table 4 further suggested that in comparison with those living with unpaved roads, individuals living with paved roads were respectively less likely to have chronic lung disease (OR = 0.76, 95%CI, 0.63 - 0.92), chronic liver disease (OR = 0.74, 95% CI, 0.55 - 0.99), chronic kidney disease (OR = 0.67, 95%CI, 0.51 - 0.89), digestive disease (OR = 0.81, 95%CI, 0.69 - 0.96), arthritis or rheumatism (OR = 0.69, 95%CI, 0.55 - 0.87), and asthma (OR = 0.67, 95%CI, 0.50 - 0.88).
5. Neighborhood-level and individual-level covariates
Living in neighborhoods with more primary care institutions was negatively associated with more NCDs (Model 2 in Table 3). Compared with those without primary care institutions in the neighborhood, individuals living with three primary care institutions or more were significantly less likely to have more NCDs (IRR = 0.94, 95% CI, 0.89 - 0.99). The disparities, however, did not exist after controlling for within-neighborhood variations.
Last, two individual-level attributes, household income, and BMI were associated with NCDs (Model 2 in Table 3). Specifically, compared with the poorest, the richest were less likely to suffer from a higher number of NCDs (IRR = 0.93, 95% CI, 0.88 - 0.98). Overweight (IRR = 1.14, 95% CI, 1.06 - 1.22) and obese subjects (IRR = 1.33, 95% CI, 1.21 - 1.46) respectively had a greater incidence rate of more NCDs compared with those with BMI less than 18.5. Subjects with BMI from18.5 to 25 had a lower incidence rate of more NCDs relative to those BMI less than 18.5, even after controlling for all other covariates (IRR = 0.90, 95%CI, 0.84 - 0.96).