Table 2. 4-year cumulative medical care days and costs according to BMI levels and metabolic health status.

	Underweight		Normal weight		Overweight		Obesity		P valuea
	(BMI <18.5)		(BMI 18.5–24.9)		(BMI 25.0–29.9)		(BMI ≥30.0)
	Healthy	Unhealthy	Healthy	Unhealthy	Healthy	Unhealthy	Healthy	Unhealthy
	(n = 664)	(n = 54)	(n = 8,465)	(n = 2,461)	(n = 2,082)	(n = 1,888)	(n = 282)	(n = 490)
Inpatient days, days/person/year
Adjusted mean	0.65	1.49	0.61	0.64	0.56	0.65	0.86	0.77	0.670
(95% CI)	(0.34–0.95)	(0.43–2.55)	(0.53–0.70)	(0.48–0.81)	(0.39–0.73)	(0.47–0.84)	(0.40–1.33)	(0.42–1.13)
Median	0	0	0	0	0	0	0	0	—
(interquartile range)	(0–0)	(0–0)	(0–0)	(0–0)	(0–0)	(0–0)	(0–0)	(0–0)
Outpatient days, days/person/year
Adjusted mean	7.7	8.9	7.4	7.9	7.6	8.7	9.2	9.7	<0.001
(95% CI)	(7.0–8.4)	(6.4–11.3)	(7.2–7.6)	(7.5–8.3)	(7.2–8.0)	(8.2–9.1)	(8.2–10.3)	(8.9–10.5)
Median	2.8	4.0	3.3	7.8	4.0	9.0	4.0	9.3	<0.001
(interquartile range)	(1.0–6.8)	(1.0–14.6)	(1.5–7.8)	(2.8–14.8)	(1.5–9.0)	(3.5–15.5)	(1.5–9.0)	(4.3–15.8)
Costs, 1,000 JPY/person/yearb
Adjusted mean	96	121	87	95	90	101	107	130	0.042
(95% CI)	(74–118)	(45–197)	(81–93)	(83–106)	(77–102)	(88–115)	(74–140)	(105–156)
Median	16	29	20	56	26	68	23	75	<0.001
(interquartile range)	(6–45)	(8–104)	(8–55)	(17–134)	(10–70)	(22–145)	(9–83)	(27–178)

BMI, body mass index; CI, confidence interval, JPY, Japanese yen.

^aP values for differences among 8 phenotypes were adjusted for age, smoking status, frequency and amount of alcohol intake, exercise habits, daily sleeping hours, and treatment of hypertension, dyslipidemia, or diabetes.

^bCost unit is expressed as 1,000 JPY (1,000 JPY = 8.8 US dollars or 7.8 euros, according to foreign exchange rates on Dec 6, 2018).