Of 4,237 patients who received more than four canisters of an SA P-agonist in 1996, 584 and 1,332, respectively, met the criteria of increasing and decreasing use (Table 3). Patients whose use decreased received significantly more canisters of SA P-agonists (13.0 vs 9.3, respectively; p < 0.0001) and had a higher mean daily ICS dose (475 vs 326 ^g/d. respectively; p < 0.0001) at baseline than those whose use increased. More plan C patients than plan E patients also increased their use over the 3 years (33.0% vs 25.2%, respectively; p = 0.004). Although there was no relationship between age and increasing use in uncontrolled patients, and the association between gender and increasing use was attenuated in the adjusted model, the receipt of social assistance remained significant. Patients on Pharmacare plan C were 1.3 times more likely than patients on plan E to increase their SA P-agonist use by at least 50%. Sensitivity analysis, varying increasing use from two to six canisters per year in controlled users, and varying increasing and decreasing use from 30 to 70% in uncontrolled users, resulted in consistent findings.
Current asthma management guidelines stipulate that a primary goal of asthma management should be the minimization of SA P-agonist use to no more than three doses per week by increasing the use of ICS and other add-on agents. Realizing that the goal of asthma management should be to improve overall asthma control rather than merely to decrease the amount of SA P-agonist use, and given the absence of other measures of control, we have used SA P-agonist use as a surrogate measure of asthma control.
Each year, approximately 5% of this population received > 12 canisters of SA P-agonist, more than half of whom were prescribed > 20 canisters, far exceeding the desired management goal. Although the total number of clients decreased from 1997 to 1998, there was no change in the distribution of the users.
Table 3—Factors Associated With Increasing SA Р-Agonist Use Among Uncontrolled Users in 1996 (n = 1,916)
|Factors||Increasing Use (n = 584)||OR (95% CI)|
|13-18 yr||56/200 (28.0)||1.0|
|19-34 yr||218/684 (31.9)||1.4 (0.96-2.0)||NS|
|35-50 yr||310/1,032 (30.0)||1.2 (0.86-1.7)|
|Male||263/808 (32.6)||1.2 (1.01-1.5)|
|ICS dose change|
|No change||94/729 (12.8)||1.0||1.0|
|> 100 ^g/d 2||210/739 (26.5)||0.43 (0.33-0.57)||0.43 (0.33-0.58)|
|100-400 ^g/d 1||129/238 (54.2)||3.4 (2.5-4.6)||3.5 (2.5-4.8)|
|401-800 ^g/d 1||70/102 (68.6)||7.3 (4.5-11.6)||6.9(4.3-11.2)|
|> 800 ^g/d 1||81/108 (75.0)||9.6 (5.9-15.7)||8.9 (5.4-14.6)|