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INSIGHTS | DRUG EXPOSURE MEASUREMENT
Hospitalization
ED/UC Visit
OCS claim
Any of the above
Thus, in studies that do not recognize the use of nebulized SABA there is likely to be
substantial misclassification of patient risk based on high SABA utilization.
The present study utilized the method described by Chan, et al, 7 being inclusive of almost all
MDI and nebulized SABA types identified in the dataset. Canister equivalents were
determined for each claim represented. A standard SABA canister size was defined to be one
containing 200 metered actuations, which encompassed more than 97% of MDI SABA claims.
More than 96% of total SABA MDI claims were for albuterol; 2.2% were for pirbuterol; and
1.6% were for levalbuterol. In the case of pirbuterol, whose standard dispensing contains 400
actuations, claims were set to two canisters. Levalbuterol was considered to be equivalent in
potency to albuterol. In cases where insufficient information was available to make the
determination, canister size was imputed using days supply of medication. Thirty days supply or
less was determined to be equivalent to one canister, 31 to 60 days supply as two canisters, etc.
FIGURE 2: SABA CANISTER FILLS 2ND QUARTER (POST-INDEX YEAR)
N=93,444
0 Canisters
1 ⁄2-3 Canisters
> 3 Canisters
0 5 10 15 20
0 Canisters (n=59,653) Percentage of Patients
1 ⁄2-3 Canisters (n= 26,525)
> 3 Canisters (n= 4,266)
32%
5%
64%
FIGURE 3: Q3 EXACERBATION INCIDENCE BY Q2 SABA USE STRATA
ED = Emergency department
UC = Urgent care
OCS = Oral corticosteroid
Nebulized SABA canister claims comprised
12% of all SABA claims. Based on the Chan
study method, canister-equivalents were
derived for each nebulized SABA claim.
The vast majority of these claims were for
albuterol or levalbuterol (considered
equivalent in potency to albuterol), in which
case one 3ml ampule was equivalent to 0.02
canister-equivalents, making fifty ampules of
3ml of medication equivalent to one canister.
The quantity of medicine is typically given in
ml in the dataset. Each ampule typically
contains 3ml of medicine and is most often
dispensed in boxes of 24, 25 or 30, each of
which was equated to a half canister of SABA.
It was determined that the most accurate
method to represent these medication
quantities was to round to the nearest halfcanister
because most boxes contained 24, 25
or 30 ampules and most claims were in
multiples of these. Less than 1% of claims
observed were clear outliers (eg, >180
ampules). For these, the maximum dose was
capped at three canister equivalents per claim.
Due to the heterogeneity of asthma
controller medications, it was elected to use
annual days supply during the pre-index and
post-index years, and days supply per quarter
for the quarterly analysis regardless of the
medication being inhaled (eg, ICS) or oral
(eg, leukotriene modifiers). Controller
medications prescribed concomitantly and
measured as covariates were assessed as the
sum of days supply provided on the claims,
a proxy for days of exposure. A similar
method was used to describe use of nasal
steroid sprays and antibiotics.
PAGE 24 IMS HEALTH ECONOMICS & OUTCOMES RESEARCH