Strategies to Assess Validity of Self-Reported Exposures ... - Impact

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Strategies to Assess Validity of Self-Reported Exposures ... - Impact

202 MCCAULEY ET AL.

TABLE 4

Frequency of Self-Reported Exposures in Gulf War Veterans

(n = 1091) and Test^Retest Reliability Coe¤cient Kappa

with Standard Error (SE) for 305 Veterans

Percentage

reporting

exposure

Agent (n ˆ 1091) Kappa (SE)

Given pyridostigmine bromide (PB) 56 0.86 (0.05)

Filled sandbags 65 0.70 (0.06)*

Worked outside 44 h/day 82 0.69 (0.06)*

Smoke from oil well ¢res 65 0.69 (0.08)*

Experimental vaccine 22 0.66 (0.07)*

Heard SCUD alarm 66 0.64 (0.06)*

Saw SCUD detonate 45 0.64 (0.06)

Ate local foods 74 0.61 (0.06)

Handled diesel/petro fuel 59 0.55 (0.10){

Insecticide cream 28 0.54 (0.09){

Took 43 PB pills/day 03 0.53 (0.13){

Anthrax vaccine 34 0.51 (0.08){

Believe exposed to CWA 59 0.44 (0.07){

Botulism vaccine 18 0.43 (0.09){

Insecticide spray 26 0.41 (0.10){

Water from local taps 34 0.38 (0.08)**

Flea collar on ankle 04 0.35 (0.19)**

Skin contact w/petro fuel 51 0.32 (0.09)**

Chemical agent-resistant coating 11 0.30 (0.18)**

Drank water from local wells 06 0.28 (0.11)**

Depleted uranium 16 0.07 (0.09)

{ Not signi¢cantly greater than 0.40 (poor agreement).

* Not signi¢cantly less than 0.70 (Excellent agreement).

** Not signi¢cantly less than 0.40 (moderate agreement).

and unexplained illness.We applied three methodological

approaches to quantify potential misclassi¢cation,

validity, and reliability of self-reported

exposure information.

Deployment Analysis

We used two data sources (self-reported information

and DoD Desert Shield/Desert Storm database

information) to determine the period of deployment

to Southwest Asia. The intermethod validity estimates

of deployment period in the Persian Gulf War

reveal large discrepancies between DoD data and

self-reported information for troops deployed at times

other than the combat period. Anecdotally, veterans

have described situations in which their assigned

units were scheduled for return to the United States,

but individuals were given opportunities to volunteer

for longer tours of duty. It is assumed that these situations

could explain some of the discrepancies. This

source of error is further demonstrated by the fact

that in our Northwest veteran sample, at least 8.5%

of the veterans whom the DoD Desert Storm/Desert

Shield database indicates were deployed to the Gulf

were never actually deployed according to accounts

from the veterans. Their units were scheduled for deployment,

but individuals factors prevented the deployment

of individuals within the units. Due to the

observed error in the DoD database and the lack of another

method to validate self-reported deployment

dates, we only included veterans for the deploymentperiod

analyses if self-report and DoD data were in

agreement (939 out of 1091 survey responders).

Examination of self-reported exposures in groups of

veterans deployed in di¡erent deployment periods can

yield valuable information about reporting validity.

There are exposures that were only possible for troops

who were in the theater-of-operations during the combat

period; these include SCUD alarms and detonations,

pyridostigmine bromide, and antibiological

warfare vaccines. Our results indicate that some veterans

who were not deployed during the combat period

do report exposures to anti-biological warfare

vaccines, SCUD alarms and detonations, PB, and chemical

warfare agents.

The rate of self-reported administration of botulinum

toxoid vaccine in noncombat veterans was 5.7%

compared to 17.8% in the combat veterans. The total

estimated number of troops that received the botulinum

toxoid vaccine is believed to be only 8000 service

members (less than 5% of combat troops), primarily in

the First Marine Division and the Army VII Corps

(IOM, 1996). The veteran population sampled in this

study did not have a greater representation of First

Marine Division or Army VII Corps troops than expected,

which suggests a general overreporting of

the botulinum toxoid vaccination.These rates also demonstrate

an over reporting of receiving the anthrax

vaccine (35.7% of the combat veterans and 9.5% of the

noncombat veterans). Many veterans probably did not

know what vaccines were being administered; however,

instead of responding ``don't know,''our data suggest

some chose ``yes''.

Pyridostigmine bromide was given to protect military

personnel from the e¡ects of organophosphate

nerve agents; pyridostigmine bromide would enhance

the therapeutic e¤cacy of atropine if atropine was administered

at the time of exposure to the nerve agent

soman (Xia et al., 1981). Commanding o¤cers were given

the pills, in distinctive blister packets, to distribute

to the troops. Pyridostigmine bromide was

intended to be taken during combat situations when

exposure to nerve agents was a possibility. Of the veterans

deployed only during Desert Shied and removed

from Southwest Asia by December 1, 1990,

11.6% reported having been given PB, while a much

smaller proportion (2.8%) of the troops deployed only

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