Racial health disparities in patients with multiple myeloma: a population-based study

In the United States, differences in health associated with race or ethnicity are particularly pronounced for multiple myeloma (MM), with mortality and incidence rates in non-Hispanic (NH) Black people more than double the rates seen in the NH-White population.¹ While treatment for MM has advanced in the past two decades, racial disparities have continued, particularly in respect to access to novel agents and clinical trials. A recent analysis of SEER-Medicare data revealed significantly lower utilization of the standard chemotherapeutic agent lenalidomide in African Americans as well as lower utilization of autologous stem cell transplantation (ASCT), both of which are necessary in the newly diagnosed and relapsed settings for MM.²

Further clarity is needed for race- and ethnicity-related differences for cases of MM in-hospitalization. As such, Al Hadidi, et al. performed a large-scale population study, recently published in Leukemia and Lymphoma, in which they collected substantial data on multiple outcomes associated with MM hospitalization, which were stratified by race and ethnicity. We summarize key results below.¹

Study design

This was a 10-year population-based study analyzing inpatient hospitalizations from 2008–2017, using information from the Nationwide Inpatient Sample.

ICD-9-CM and ICD-10-CM codes were used to identify patients with MM as well as outcomes. The study included all hospitalizations in adults (≥18 years) with an occurrence of MM in the discharge records.

The variables associated with MM hospitalization that were investigated in this study are summarized in Figure 1.

ICU, intensive care unit; NH-Black, Non-Hispanic-Black; NH-White, Non-Hispanic-White.
*Adapted from Al Hadidi, et al.
^†lowest quartile, 2nd quartile, 3rd quartile, highest quartile.

 Results

Hospitalization rate

A total of 913,967 patients with MM were identified in the Nationwide Inpatient Sample, and the total in-hospitalization mortality rate was 5.3% (48,757).

The prevalence of MM-related hospitalizations was higher in NH-Black patients compared with NH-White patients (476.0 vs 305.6, per 100,000 hospitalizations; p < 0.001).

The prevalence of MM-related hospitalizations was also significantly higher in elderly patients, males, earners in the lower income quartile, and those who self-pay (Table 1).

Table 1. Prevalence of hospitalizations and mortality rate in patients with multiple myeloma*

NH-Black, non-Hispanic Black; NH-other, non-Hispanic other; NW-White, non-Hispanic White. *Data from Hadidi, et al.1
Variables	Myeloma		In-hospital mortality		p value
	n = 913,967	Prevalence, per 100,000 hospitalizations	n = 48,757	Incidence of in-hospital death, %
Age					<0.01
18–34	3,301	5.9	63	1.9
35–49	48,698	111.3	1,656	3.4
50–64	283,350	394.3	12,427	4.4
65+	578,618	505.4	34,611	6.0
Race/ethnicity					<0.01
NH-              White	544,670	305.6	29,073	5.3
NH-              Black	186,846	476.0	9,825	5.3
Hispanic	64,541	242.6	3,324	5.2
NH-              other	42,565	265.2	2,622	6.2
Missing	75,347	292.9	3,914	5.2
Sex					<0.01
Male	496,555	424.7	27,624	5.6
Female	417,099	247.0	21,118	5.1
Missing	314	349.7	15	4.8
Zip income quartile					<0.01
Lowest	245,875	291.4	13,517	5.5
2nd	222,359	301.9	11,267	5.1
3rd	217,727	331.1	11,598	5.3
Highest	210,294	377.9	11,344	5.4
Missing	17,713	274.4	1,032	5.8
Primary payer					<0.01
Medicare	610,759	463.3	33,284	5.4
Medicaid	53,735	115.3	2,523	4.7
Private	213,964	260.1	10,081	4.7
Self-pay	33,507	136.2	2,737	8.2
Missing	2,002	348.9	132	6.6

The rate of MM-related in-hospital mortality was higher in Hispanic people compared with NH-White and NH-Black patients (6.2% vs 5.3%; p < 0.001).

Hospital treatment access

Overall, NH-Black patients with MM received fewer ASCTs compared with NH-White patients (2.8 vs 3.8%), fewer palliative care consultations (4.0% vs 4.6%), less chemotherapy (10.8% vs 11.2%), and more intensive care (5.3% vs 4.3%). In contrast, NH-Black patients received more in-patient blood product transfusions than NH-White patients (23.0 vs 21.1%).

Hispanic patients received on average more ASCT and more inpatient chemotherapy than NH-White patients (Table 2).

Table 2. In-hospitalization therapeutic modality use stratified by race*

ASCT, Autologous stem cell transplant; ICU, intensive care unit; NH-Black, Non-Hispanic-Black; NH-White, Non-Hispanic-White. *Data from Hadidi, et al.1
Therapeutic modality, %	NH-White	NH-Black	Hispanic	p value
ASCT	3.8	2.8	4.0	<0.01
Blood product transfusion	21.1	23.0	21.1	<0.01
Palliative care consultation	4.6	4.0	3.8	<0.01
Chemotherapy use	11.2	10.8	12.8	<0.01
Inpatient bone marrow biopsy	6.6	7.7	8.8	<0.01
ICU utilization	4.3	5.3	4.4	<0.01

Following multivariate analysis, the authors identified trends of lower utilizations of ASCT, chemotherapy, and palliative care and higher utilization of ICU, blood products, and inpatient bone marrow biopsy in NH-Black patients compared with NH-White patients. Multivariate analysis also showed that Hispanic patients has significantly reduced palliative care consultation compared with NH-White patients (Table 3).

Table 3. Multivariate analysis for in-hospitalization of multiple myeloma patients*

ASCT, autologous stem cell transplant; CI, confidence interval; ICU, Intensive care unit; NH-Black, Non-Hispanic-Black; NH-White, Non-Hispanic-White; OR, odds ratio. *Data from Hadidi, et al.1
Outcomes (NH-White patients as reference)	OR	95% CI	p value
In-hospital death
NH-Black	1.02	0.96–1.08	0.50
Hispanic	0.99	0.90–1.08	0.74
ASCT
NH-Black	0.68	0.58–0.79	<0.01
Hispanic	0.91	0.74–1.12	0.38
Blood product transfusion
NH-Black	1.12	1.06–1.18	<0.01
Hispanic	1.01	0.92–1.10	0.90
Chemotherapy use
NH-Black	0.91	0.84–0.98	0.02
Hispanic	1.04	0.92–1.18	0.52
Palliative care consultation
NH-Black	0.91	0.85–0.97	0.01
Hispanic	0.83	0.75–0.93	<0.01
ICU utilization
NH-Black	1.24	1.17–1.32	<0.01
Hispanic	1.00	0.91–1.11	0.95

Length and cost of hospital stay

The mean length of stay for patients hospitalized was one day longer for Hispanic and NH-Black patients compared with NH-White patients, while the mean cost of hospitalization (USD) was higher for NH-Black patients versus NH-White patients (Table 4).

Table 4. The mean cost of hospitalization and mean length of stay stratified by race*

NH-Black, Non-Hispanic-Black; NH-White, Non-Hispanic-White; SD, standard deviation; USD, U.S dollars. *Data from Hadidi, et al.1 †p value calculated using ANOVA.
	NH-White	NH-Black	Hispanic	p value†
Mean cost of hospitalization (SD), USD	16,516.8 (322.8)	16,971.91 (285.9)	19,190.5 (395.6)	0.62
Mean length of stay (SD), days	6.9 (1.2)	7.83074 (1.3)	7.7 (1.6)	0.38

Average annual percent change

Overall, there was a statistically significant decline of in-hospital mortality among all MM patients when measured by an average annual percentage change (AAPC) (AAPC: -3.0; 95% confidence interval [CI], −4.2 to −1.8; p < 0.001). However, when stratifying by race, NH-White patients had the most significant in-hospital mortality improvement with an AAPC of -3.8 (95% CI, −5.4 to −2.3; p < 0.001). For NH-Black patients, the decline of in-hospital mortality was not statistically significant (AAPC: -2.2, 95% CI, −4.7 – 0.4).

Conclusion

This large-scale population study provided further evidence for a racial/ethnic imbalance regarding access to healthcare and disease burden in patients with MM. NH-Black patients had a higher prevalence of hospitalisations and greater in-hospitalization mortality compared with NH-White patients, while being provided fewer vital therapeutic modalities including ASCT and chemotherapy. Both NH-black and Hispanic patients also received fewer palliative care consultations to help manage symptoms. These differences call for urgent action to improve the current healthcare system in order to provide equity for the population suffering from MM in the US.