The following text was automatically extracted from the image on this page using optical character recognition software:
Page 2 December 3, 2001 DPN
Study Results
A total of 5,272 students were identified
as having attended Mesita and E.B. Jones
Elementary schools from 1948 through
1970; 3,891 from Mesita and 1,384 from
E.B. Jones. Several students reported at-
tending both schools. Current addresses
were identified for 33% (n=1,248) of
former Mesita students and 32% (n=432)
of former E.B. Jones students. Forty-four
percent of the former Mesita students
and 20% of the E.B. Jones students who
were contacted returned questionnaires.
Fourteen cases of definite and probable
MS were identified among former Mesita
students. No cases were reported for the
E.B. Jones cohort. Using the 14 cases of
MS and dividing by the total combined
cohort of 5,272 students, the crude MS
prevalence estimate for the combined
school cohort is 266 cases per 100,000
population (95% Confidence Interval or
CI = 145 to 445 per 100,000). Using the
14 MS cases and dividing by the total
Mesita cohort of 3,891, the crude MS
prevalence for the Mesita cohort is 360
per 100,000 (95% CI = 197 to 603 per
100,000). The crude prevalence estimates
for both the combined cohort and the
Mesita cohort are higher than previously
published U.S. prevalence estimates for
MS which range from 87 to 160 per
100,000.
Standardized morbidity ratios (SMRs)
were also calculated for the combined
Mesita and E.B. Jones cohorts and for
the Mesita cohort separately. Using
data from the 1989 to 1994 National
Health Interview Survey (NHIS), the
SMR for the combined cohort was 1.42
(95% CI = 0.78 to 2.40) indicating an
elevated, but not statistically significant
risk of MS among the combined cohort.
For the Mesita cohort, the SMR was
1.93 (95% CI = 1.06 to 3.24) indicating
a statistically significant twofold
increased risk of MS.
Conclusions
This study was designed to (1) identify
the number of people with MS in the
school cohorts, (2) determine if the num-
ber of people with MS was more than was
expected based on national prevalence
estimates, and (3) review historic environ-
mental and biologic sampling data.
Fourteen cases of MS among former
Mesita students were identified and con-
firmed. No cases were reported among
former E.B. Jones students. The number
of people with MS among former Mesita
students is twice as high as expected,
based on national estimates. Limited
historic environmental and biological data
were identified for the study area. These
results are reported in a separate adden-
dum to the report. This study was not
designed to investigate the specific cause
or causes of MS, and the results cannot
explain why there is an excess of MS
among the former Mesita students.
Recommendations
Based on the findings of this study, TDH
recommends four activities:
" Conduct an annual survey of the
Mesita and E.B. Jones cohorts for
a minimum of two additional years to
determine if any additional people
are diagnosed with MS. All former
students of these schools are encouraged
to participate in the surveys.
" Develop current MS prevalence estimates
for Texas.
" Reanalyze the El Paso MS cluster
data when Texas prevalence estimates
become available.
* Conduct a national multi-site case
control study to examine metals
exposure as a possible etiologic risk
factor for MS. Combining MS cases
from multiple sites around the United
States may provide the statistical
power needed to study the association
between metals exposure and MS.
Participants in the El Paso study
should be included in the multisite
study.
Prepared by Judy Henry, MS, and
Laurie Wagner, TDH Epidemiology and
Toxicology Division.
The full report of this investigation is available at the TDH Environmental Epidemiology and
Toxicology Division Website: www.tdh.state.tx.us /epitox /ms /msmain.htm.
Page 2
December 3, 2001
DPN