Results from the binomial regression model of the proportions of IDUs who were Hispanic by data source are in Table . Anti-logit transforming the intercept gives the average predicted Hispanic proportion value among IAIDS cases—0.061 in 1992. Both the linear (years since 1992) and quadratic (years since 1992 squared) slopes are positive, but only the linear term is significant, indicating a linear increase over time on average. The CTS dummy code was not significant, indicating that Hispanic IDU proportions in CTS data were not different from those in IAIDS data. However, the TEDS dummy code was significant in the positive direction, indicating that TEDS Hispanic IDU proportions were almost 20% higher than those in IAIDS—0.073 on average in 1992.
Binomial mixed-effects regression results for the proportions of injection drug users who were Hispanic in three data sources, 1992–2002
Pearson correlations among the three estimates of the proportions of IDUs who were Hispanic showed good consistency. Correlations between CTS and TEDS proportions ranged from 0.90 to 0.93 across years (mean
0.91), while those between CTS and IAIDS ranged from 0.51 to 0.85 (mean
0.74) and those between TEDS and IAIDS ranged from 0.60 to 0.80 (mean
We calculated a single yearly proportion of IDUs who were Hispanic in each MSA by averaging the set of proportions from the three sources. We multiplied the averaged proportions by published estimates of the populations of IDUs of all racial/ethnic groups and divided the results by the respective Hispanic MSA populations to produce population prevalence estimates.
Descriptive data for the yearly Hispanic IDU population prevalence estimates are in Table . The estimates show a substantial decline from 1992 (mean
133) to 2002 (mean
93; units are per 10,000 Hispanics aged 15–64). Hispanic IDU prevalence declined more sharply initially, then more slowly, with fluctuations, forming a slightly curvilinear relationship with time. Figure depicts average IDU prevalence among Hispanic residents, compared with previously published data for non-Hispanic Black and non-Hispanic White residents across time.9
Generally, estimates of Hispanic IDU population prevalence were higher than published estimates for non-Hispanic White residents and lower than published estimates for non-Hispanic Black residents.
Estimated prevalence of Hispanic injection drug users per 10,000 Hispanic residents aged 15–64, 1992–2002
Figure 1. Average population prevalence of injection drug users by racial/ethnic group and year, 1992–2002. N=96 metropolitan statistical areas. Data for non-Hispanic White and non-Hispanic Black IDUs were previously published9 and exclude (more ...)
Yearly Pearson correlations with drug-related mortality rates and hepatitis C mortality rates among Hispanics are in Table . Correlations with drug-related mortality ranged from 0.36 to 0.62 (mean
0.48). Correlations with hepatitis C mortality ranged from 0.43 to 0.73 (mean
Pearson correlations of estimated Hispanic injection drug user population prevalence rates with mortality rates for drug-related deaths and hepatitis C deaths among Hispanics, 1992–2002
Results of the polynomial mixed-effects model testing for trend over time in logged Hispanic IDU population prevalence rates are in Table . The antilog of the intercept, representing Hispanic IDU population prevalence in 1992, is 132.4 Hispanic IDUs per 10,000 Hispanics. The average annual logged linear decline is −0.070; however, the positive polynomial term (0.0028) indicates a flattening of the slope over time. The antilog of the average year-to-year decline, including linear and quadratic terms, was 8.6 per 10,000 from 1992 to 1993 but lessened to 1.4 per 10,000 from 2001 to 2002. The predicted value for 2002 is 87.1 per 10,000, which approximates the observed median estimate.
Linear mixed-effects regression results of logged Hispanic injection drug user population prevalence, 1992–2002
The sum of the number of Hispanic IDUs in these MSAs by Census region is presented in Figure . An increase in the most recent years of the study period is evident for the northeast region, with less change in the other regions.
Figure 2. Sum of Hispanic injection drug users by Census region and year, 1992–2002. N=96 metropolitan statistical areas.
MSA-specific results are presented in the Appendix
. The largest populations of Hispanic IDUs were generally in the MSAs most populated by Hispanics. Averaging the most recent 3 years (2000–2002), the five MSAs with the largest Hispanic IDU populations were Los Angeles–Long Beach, CA (40,375); New York, NY (36,999); San Juan–Bayamon, PR (15,333); Boston, MA–NH (9,872); and San Antonio, TX (9,266). However, the highest IDU prevalence rates among Hispanic residents tended to be in smaller northeastern MSAs. Averaging the most recent 3 years, the five MSAs with the highest prevalence rates (per 10,000 Hispanic residents) were Allentown–Bethlehem–Easton, PA (756); Springfield, MA (752); Hartford, CT (694); Harrisburg–Lebanon–Carlisle, PA (652); and Buffalo–Niagara Falls, NY (533).
We calculated percent change values comparing averages of the earliest (1992–1994) and latest (2000–2002) 3 years of data. Hispanic IDU population prevalence decreased in 79 MSAs—by 10% or more in 70 MSAs and by 50% or more in 13 MSAs. Prevalence increased in 17 MSAs—by 10% or more in eight MSAs (Boston, MA–NH 38%; Baltimore, MD 35%; Honolulu, HI 25%; Toledo, OH and Stockton–Lodi, CA 14%; Pittsburgh, PA and Springfield, MA 12%) and by 50% or more in one MSA (Youngstown–Warren, OH 64%).
Lastly, to extend the analysis to more recent years, for which overall IDU prevalence has not been published, we compared the proportion of IDUs that was Hispanic between 2003 and 2007. This proportion did not change significantly between 2003 and 2007 (linear estimate [Est.]
−0.0057, standard error [SE]
0.1158; quadratic Est. = 0.0004, SE
0.0046) across MSAs. We then compared change in the proportion averaged over 2002–2004 to the proportion averaged over 2005–2007 (change could not be estimated for four MSAs with missing data—Gary, IN; San Juan–Bayamon, PR; Tucson, AZ; and Wichita, KS). Of the remaining 92 MSAs, the proportion of IDUs that was Hispanic decreased in 42 (52%) and increased in 44 (48%). Of these 44, 19 increased by more than 10%, and 13 increased by more than 20% (Dayton–Springfield, OH 60%; Greenville–Spartanburg–Anderson, SC 53%; Las Vegas, NV–AZ 49%; New Orleans, LA 45%; Norfolk–Virginia Beach–Newport News, VA–NC 39%; Atlanta, GA 37%; Little Rock–North Little Rock, AR 33%; Richmond–Petersburg, VA 32%; St. Louis, MO–IL 29%; Baltimore, MD 26%; Tacoma, WA 23%; Jacksonville, FL 23%; Detroit, MI 22%).