Trends in prevalence and treatment rate of anemia in the U.S. population: cross-sectional study using data from NHANES 2005–2018

Figures & data

Table 1. Sample characteristics of seven survey cycles data extracted from NHANES between 2005 and 2018.

Variable	Level	N	%	SE	P-value
Age group	20–39 yrs	11,195	37.17	0.61	<.001
	40–59 yrs	10,251	36.65	0.47
	60+ yrs	10,926	26.18	0.54
Anemia	No	29,016	92.94	0.26	<.001
	Yes	3356	7.06	0.26
Birth place	U.S.	23,632	83.46	0.72	<.001
	Others	8740	16.54	0.72
Education	Less than High School	7833	15.59	0.55	<.001
	High School graduate	7413	23.16	0.49
	Some college or AA	9648	31.52	0.46
	College graduate or above	7478	29.73	0.91
Insurance	Yes	25,703	83.16	0.53	<.001
	No	6669	16.84	0.53
Treatment	Yes	1390	3.62	0.16	<.001
	No	30,982	96.38	0.16
Poverty income ratio	≤1.3	10,290	21.39	0.59	<.001
	1.3–3.5	12,194	35.64	0.59
	≥3.5	9888	42.97	0.93
Race	HSP	7839	13.31	0.85	<.001
	NHW	14,198	68.55	1.25
	NHB	6750	10.64	0.67
	other	3585	7.5	0.38
Sex	Male	15,660	47.98	0.26	<.001
	Female	16,712	52.02	0.26
Cycle	2005–2006	4205	13.69	0.77	0.778
	2007–2008	4790	13.57	0.75
	2009–2010	5088	13.76	0.76
	2011–2012	4523	14.52	0.86
	2013–2014	4879	14.94	0.74
	2015–2016	4579	14.75	0.75
	2017–2018	4308	14.77	0.51

Note: N, raw frequency; %, weighted percentage; SE, standard error of the weighted percentage; P-value, Chi-square tests for equal proportions.

Table 2. The general anemia prevalence and treatment rates across seven survey cycles.

	Anemia			Treatment
Cycle	N	%	SE	N	%	SE
2005–2006	400	5.71	0.51	58	19.26	1.89
2007–2008	421	6.43	0.91	80	20.47	3.86
2009–2010	476	7.15	0.45	94	20.16	1.88
2011–2012	538	7.85	0.87	74	13.62	1.8
2013–2014	518	7.67	0.65	75	14.54	2.28
2015–2016	539	7.63	0.71	93	15.02	2.22
2017–2018	464	6.86	0.63	103	22.25	2.46
	p-value < .001			p-value = .148

Figure 1. The anemia weighted prevalence from 2005 to 2018 by subgroups: (a) age group, (b) sex, (c) race, (4) education, (5) poverty income ratio, (f) birthplace. The error bars represent the standard errors obtained by Taylor series linearization.

Table 3. Multiple logistic regression models for anemia status as the dependent variable.

Predictor	Level	Unadjusted OR (LCL, UCL)	Adjusted OR (LCL, UCL)
Age group	20–39 yrs	Ref.	Ref.
	40–59 yrs	1.06 (0.94,1.19)	1.17 (1.04–1.32)
	60+ yrs	1.92 (1.71, 2.17)	2.15 (1.90–2.43)
Sex	Female	Ref.	Ref.
	Male	0.45 (0.41,0.50)	0.47 (0.42–0.53)
Race	NHB	Ref.	Ref.
	HSP	0.35 (0.31,0.40)	0.34 (0.29–0.40)
	NHW	0.22(0.19, 0.25)	0.22 (0.19–0.25)
	Other	0.35 (0.31, 0.41)	0.35 (0.30–0.41)
Education level	Less than High School	Ref.	Ref.
	College graduate or above	0.52 (0.44,0.61)	0.84 (0.70–1.01)
	High School graduate	0.71 (0.63, 0.80)	0.88 (0.77–1.00)
	Some college or AA degree	0.63 (0.55, 0.72)	0.80 (0.69–0.93)
Insurance	No	Ref.	Ref.
	Yes	1.23 (1.11, 1.37)	1.40 (1.26–1.57)
Birthplace	Other	Ref.	Ref.
	U.S.	0.78 (0.69, 0.88)	0.88 (0.77–1.01)
PIR	≤1.3	Ref.	Ref.
	1.3–3.5	0.75 (0.67, 0.85)	0.85 (0.76–0.95)
	≥3.5	0.44 (0.39, 0.50)	0.60 (0.53–0.69)

Note: Unadjusted OR, odds ratio without adjusting for other covariates; Adjusted OR, odds ratio adjusting for other covariates; LCL, lower confidence limit; UCL, upper confidence limit; PIR, poverty income ratio.

Figure 2. The anemia treatment rates from 2005 to 2018 by subgroups: (a) age group, (b) sex, (c) birthplace, (d) insurance. The error bars represent the standard errors obtained by Taylor series linearization.

Table 4. Multiple logistic regression models for anemia treatment as the dependent variable.

Predictor	Level	Unadjusted OR (LCL, UCL)	Adjusted OR (LCL, UCL)
Age group	20–39 yrs	Ref.	Ref.
	40–59 yrs	1.26 (0.93, 1.71)	1.49 (1.09–2.03)
	60+ yrs	1.27 (1.00, 1.62)	1.51 (1.10–2.09)
Sex	Female	Ref.	Ref.
	Male	0.60 (0.46, 0.78)	0.53 (0.38–0.72)
Race	NHB	Ref.	Ref.
	HSP	0.85 (0.63, 1.34)	1.24 (0.81–1.89)
	NHW	0.99 (0.74, 1.32)	0.98 (0.71–1.36)
	Other	0.87 (0.59, 1.29)	1.44 (0.90–2.32)
Education level	Less than High School	Ref.	Ref.
	College graduate or above	0.88 (0.63, 1.24)	0.89 (0.61–1.31)
	High School graduate	1.04 (0.78, 1.38)	0.91 (0.67–1.25)
	Some college or AA degree	0.95 (0.74, 1.22)	0.90 (0.64–1.25)
Insurance	No	Ref.	Ref.
	Yes	1.76 (1.32, 2.34)	1.80 (1.24–2.61)
Birthplace	Other	Ref.	Ref.
	U.S.	1.58 (1.21, 2.07)	1.88 (1.22–2.89)
PIR	≤1.3	Ref.	Ref.
	1.3–3.5	1.10 (0.85, 1.43)	0.96 (0.72–1.27)
	≥3.5	0.86 (0.62, 1.18)	0.70 (0.48–1.01)

Note: Unadjusted OR, odds ratio without adjusting for other covariates; Adjusted OR, odds ratio adjusting for other covariates; LCL, lower confidence limit; UCL, upper confidence limit; PIR, poverty income ratio.

Data availability statement

The data used in this study can be downloaded from NHANES websites: https://www.cdc.gov/nchs/nhanes/index.htm. Code availability: The code used in this study is available upon request.