Association of mitochondrial DNA copy number with self-rated health status

Figures & data

Table 1 Basic characteristics and mitochondrial DNA information of study subjects, stratified by perceived general health

	Overall cohort (n=944)	Perceived general health
		Excellent/very good (n=601)	Good (n=287)	Fair/poor (n=54)	P-value*
Age,	60.5	57.0	64	66.5	<0.001
Median (25th–75th percentile)	(51.0, 71.0)	(48.0, 67.0)	(53.0, 72.0)	(55.3, 78.0)
Female sex, N (%)	470 (49.8)	326 (54.2)	121 (42.2)	22 (40.7)	<0.001
BMI	28.2	27.1	30.2	30.3	<0.001
Median (25th–75th percentile)	(24.9, 32.4)	(24.3, 31.0)	(26.9, 34.5)	(26.4, 35.4)
Education, N (%)					<0.001
High school or less	167 (18.0)	79 (13.3)	70 (25.0)	18 (36.0)
Some college	326 (35.2)	201 (33.8)	110 (39.3)	15 (30.0)
College	257 (27.7)	182 (30.6)	61 (21.8)	13 (26.0)
Graduate/professional	177 (19.1)	133 (22.4)	39 (13.9)	4 (8.0)
Alcohol consumption, n (%)					<0.001
Never	171 (18.1)	86 (12.8)	63 (22.0)	22 (40.7)
Once a month or less	206 (21.8)	188 (28.0)	71 (24.7)	16 (29.6)
2–4 times a month	245 (26.0)	168 (25.0)	69 (24.0)	8 (14.8)
2–5 times a week	254 (26.9)	184 (27.4)	63 (22.0)	7 (13.0)
6+ a week	67 (7.1)	45 (6.7)	21 (7.3)	1 (1.9)
Smoking ever, n (%)	360 (38.1)	194 (32.6)	141 (50.2)	25 (48.1)	<0.001
Number of comorbidities	3	3	5	7	<0.001
Median (25th–75th percentile)	(2, 6)	(1, 4)	(3, 7)	(5, 9)
Mitochondrial haplogroup, N (%)					0.98
HV (HV, H, and V)	467 (49.4)	294 (48.9)	144 (50.2)	28 (51.9)
J	90 (9.5)	58 (9.7)	26 (9.1)	5 (9.3)
T	99 (10.5)	66 (11.0)	30 (10.5)	3 (5.6)
U (minus K)	146 (15.5)	91 (15.1)	45 (15.7)	10 (18.5)
K	71 (7.5)	47 (7.8)	20 (7.0)	4 (7.4)
Other european groups	55 (5.9)	36 (6.0)	17 (5.9)	3 (5.6)
Non-european groups	15 (1.6)	9 (1.5)	5 (1.7)	1 (1.9)
Mitochondrial copy number	88.9	90.7	86.1	82.9	<0.001
Median (25th–75th percentile)	(77.6, 101.1)	(79.2, 103.3)	(75.8, 97.4)	(72.4, 99.7)

Notes:

* P-values are to test association between each variable and perceived general heath univariately, using proportional odds model.

Abbreviation: BMI, body mass index.

Figure 1 The relationship between age and self-rated health stratified by sex in the study cohort.

Note: excellent self-rated health decreases with age in both males and females.

Figure 2 The relationship between age and mtDNA copy number in the study cohort, stratified by sex.

Notes: Age is associated with a lower mtDNA copy number. The mtDNA copy number remains higher in women than in men.
Abbreviation: mtDNA, mitochondrial DNA.

Table 2 Association between mitochondrial DNA copy number and perceived general health

	Model 1a: ORb (95% CI)	Model 2a: ORb (95% CI)	Model 3a: ORb (95% CI)
Age: linear quadratic	0.32 (0.10, 0.99)	11.70 (3.09, 43.36)	14.01 (3.44, 55.70)
	0.12 (0.06, 0.24)	2.52 (1.01, 6.32)	1.40 (0.53, 3.71)
Female sex	1.35 (1.02, 1.78)	1.44 (1.07, 1.94)	1.31 (0.96, 1.79)
Number of comorbidities	–	0.63 (0.58, 0.l68)	0.65 (0.60, 0.70)
Body mass index: linear quadratic	–	–	0.03 (0.01, 0.13)
			0.31 (0.06, 1.70)
Mitochondrial copy number, log-transformed	2.33 (1.26, 4.39)	2.28 (1.18, 4.47)	2.01 (1.00, 4.09)

Notes:

a Model 1: adjusting for age (in a quadratic form) and sex; Model 2: adjusting for age (in a quadratic form), sex, and number of comorbidities; Model 3: adjusting for age (in a quadratic form), sex, number of comorbidities, and body mass index (in a quadratic form).

b OR is the odds of having perceived general health in the better direction, compared to the odds in the worse direction for a given category.