POVERTY, YOUTH, AND MINORITY ETHNICITY RAISE RISK OF ASTHMA HOSPITALIZATIONS

NEW YORK CITY-Low income and other socioeconomic factors play an important role in the alarmingly high rates of hospitalization for asthma in America's cities. That was the conclusion of researchers who studied asthma hospitalization in New York City, which has some of the highest admission rates for asthma ever reported in the United States.¹

Among the city's five boroughs, the situation was worst in the two most economically depressed--the Bronx and Brooklyn--which had asthma hospitalization rates of 75 and 52 per 10,000, respectively. The rate was only 23 per 10,000 in the richest borough, Staten Island, and 46 per 10,000 for New York City overall. The study also uncovered linkages between minority ethnicity and age younger than 18 years with a greater likelihood of asthma hospitalization.

"The huge disparity between the neighborhoods with the lowest and highest asthma hospitalization rates was our most striking finding," commented lead study author Luz Claudio, PhD, in an interview with Respiratory Reviews. "When we compared the top and bottom quintiles for asthma hospitalization, we found a 21-fold difference in their admission rates."

The researchers conducted their study at the request of community leaders in Harlem and the Bronx, who were worried about rising asthma morbidity and mortality. "These communities wanted to know if they had more asthma admissions than the rest of New York City, so we did a systematic study to address their concerns," said Dr. Claudio, who is Director of the Community Outreach and Education Program at Mount Sinai School of Medicine in New York City.

She and her team analyzed demographic and hospital discharge information for all of New York City by zip code, excluding three nonresidential areas--Rockefeller Center in Manhattan and LaGuardia Airport and John F. Kennedy Airport, which are both located in Queens. They collected the information with INFOSHARE^TM software that consolidates hospitalization data from the Statistics Planning and Area-wide Research Council (SPARCS).

The most recent demographic and hospital discharge data were from 1994. These data were based on projections from the 1990 National Census and included median household income, population identified as African American and/or Latino, and age distribution. "The International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis code 493 was used to identify the asthma hospitalization discharge diagnosis," noted the researchers.

As part of their data analysis, they made two maps of New York City. On one, they plotted asthma hospitalization rates by quintile for each zip code. On the other, they plotted median household income by quintile for each zip code.

The asthma hospitalization map showed that zip codes with high asthma admissions were clustered, not randomly distributed throughout the city. These clusters "were generally surrounded by zip code areas with the next highest levels of asthma admission rates," the researchers pointed out.

Superimposing the two maps clearly illustrated the relationship between high asthma hospitalization and low income. In the Bronx, for example, where asthma hospitalization was highest, median household income was lowest ($25,455 per year versus nearly $47,500 for Staten Island and $35,700 for New York City overall).

"The highest asthma hospitalization rate for a specific zip code was 222 per 10,000 residents, and that was in East Harlem," Dr. Claudio told Respiratory Reviews. "That's more than two times the highest asthma hospitalization rate reported in another similar study, which was about 96 per 10,000 for one zip code in Seattle."

Results showed that the population of the southern part of East Harlem was largely African American and Latino. Its median household income was only about $18,700 per year, and nearly 29% of its population was age 17 years or younger. Demographics were similar in Bushwick (Brooklyn), Mott Haven, and Melrose (the Bronx), and other neighborhoods with the highest asthma hospitalization rates.

The opposite demographics tended to be found where asthma admissions were virtually nonexistent, including the Queens and Manhattan communities of Glen Oaks, Fort Tilden, New Hyde Park, North Shore, Wall Street, and Trinity. Typically, the median household income in these areas was over $47,000, African Americans and Latinos made up less than 20% of the population, and less than 20% of residents were age 17 years or younger. However, there were exceptions to these generalities. In Trinity, for example, about 75% were African American and Latino and the median household income was only about $22,700 a year. In Fort Tilden, approximately 28% were African American.

Statistical analysis found a particularly strong positive correlation between asthma hospitalization and the percentage of African Americans and Latinos in the community. A positive correlation also emerged between asthma hospitalization and the percentage of residents younger than age 18 years. There was a strong inverse correlation between asthma admission and median household income.

There are several explanations for the increased likelihood of asthma hospitalization this study found. Low-income minorities may not have access to proper preventive care, for example. They may also have poorer, more run-down housing that increases exposure to indoor air pollutants; and they more often live near facilities that emit pollutants. "Our results are [also] consistent with the notion that children are more susceptible to asthma attacks than adults," the researchers added.

Their study has already proven useful in designing asthma interventions. "We submitted our data to the Environmental Protection Agency, and they used it to justify setting up new air pollution monitors for fine particulate matter," said Dr. Claudio. "The monitors are actually going to be placed very soon in some of the neighborhoods we identified as having the highest asthma admissions. So it's nice to see that research like this can have that kind of impact, and that community participation was an important part of this process."

-Timothy Begany

Reference
1. Claudio L, Tulton L, Doucette J, Landrigan PJ. Socioeconomic factors and asthma hospitalization rates in New York City. J Asthma. 1999; 36:343-350.