Economic Impact of an Asthma Education Programme on Medical Care Utilisation

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1 ORIGINAL RESEARCH ARTICLE Dis Manage Health Outcomes 2000 Sep; 8 (3): /00/ /$20.00/0 Adis International Limited. All rights reserved. Economic Impact of an Asthma Education Programme on Medical Care Utilisation Dong-Churl Suh, 1 Soung-Kook Shin, 1 Robert M. Voytovich 2 and Allan Zimmerman 2 1 Rutgers-The State University of New Jersey, College of Pharmacy, Piscataway, New Jersey, USA 2 National Prescription Administrators, Inc., East Hanover, New Jersey, USA Abstract Objective: To determine the economic impact of an asthma education programme. Design and setting: The study was population-based and used claims data to determine changes in the resources used by identified patients with asthma 9 months before (January 1997 to September 1997) and 9 months after (January 1998 to September 1998) the implementation of the asthma education programme. Direct medical costs and frequency of use of services for asthma treatment before and after implementation of the asthma intervention programme were compared to evaluate the impact of the programme on medical treatment costs. Perspective: Third-party payer. Patients: Patients who were diagnosed with asthma at least 12 months prior to the implementation of the intervention were included; all patients were members of a union health and welfare fund, located in the northeastern part of the US. Of the 5527 patients, 2235 were included in the intervention group and 3292 patients served as the control group. Intervention: The asthma education focused on asthma prevention and treatment, recognition and elimination of asthma triggers, and compliance with asthma medications. The programme also included therapy management intervention with physicians, drug product selection and compliance intervention when needed. Main outcome measures and results: The total asthma treatment cost decreased from $US499 to $US415 per patient (a 17% reduction; p = ) in the intervention group and decreased from $US227 to $US217 in the control group (a 4% decrease; p = ) [1997 values]. The decrease in the intervention group was significantly greater than that in the control group after controlling for the differences in treatment costs before the intervention (p = ). The average cost per patient associated with hospitalisation, emergency room visits, physician visits and asthma medications decreased by 13%, 29%, 36% and 18%, respectively, after the intervention in the study group. There was a 9% reduction in the frequency of hospitalisations, a 27% reduction in emergency room usage, a 27% reduction in physician office visits and a 6% reduction in the number of prescriptions per patient for asthma medications after the intervention in the study group.

2 160 Suh et al. Conclusions: Significant reductions in overall asthma treatment costs were observed after the implementation of the asthma education programme. Therefore, intense patient education and management should be advocated to reduce treatment costs in patients with asthma. Asthma is a common chronic respiratory disorder that affects 14 to 15 million people in the US. The prevalence of asthma is high (5.6% of the general US population in 1994) and is expected to continue to rise. [1] The economic impact of asthma in the US was estimated at $US6.2 billion in 1990, up from $US4.4 billion in [2,3] Direct medical costs for asthma accounted for $US3.6 billion ($US1.6 billion was spent on hospitalisation, $US1 billion on medications, approximately $US600 million on physician-related services and $US300 million on emergency room services) and indirect costs accounted for $US2.6 million. Average total charges for asthma treatment were estimated at $US5670 per patient with an acute episode of asthma in [3] Average charges for hospitalisation ($US5260) accounted for 92% of these costs, with the average length of hospital stay being 3.5 days and the average charges for a visit to the general practitioner being approximately $US460 per episode. The US National Heart, Lung, and Blood Institute (NHLBI) has developed guidelines for the diagnosis and efficient management of asthma. [4-6] These guidelines include recommendations for the proper use of a wide range of medications available for the treatment of this condition as well as education to promote more effective self-management. It has been shown that a comprehensive asthma management programme based on these guidelines decreases both the occurrence of acute asthma events and the cost of treatment. [7,8] It has been assumed that educating patients with asthma may yield economic benefits, therefore a number of educational programmes have been developed for the management of asthma, based on the theories of behavioural change. [9] It has been found that the majority of patients who present at the emergency room with asthma generally have very poor asthma control, have chronic exposure to environmental triggers and display poor management of exacerbations, which occur as a direct result of poor patient education. [10] Comprehensive educational programmes aimed at increasing adherence to treatment and improving self-management skills have proven to be beneficial in reducing asthma treatment costs and improving outcomes in patients with mild to moderately severe asthma. [11-15] Although many previous studies have shown that asthma education can improve self-management and, consequently, reduce the number of emergency visits and hospitalisations, [7,8,13-21] the results of these studies may not be generalised because many of these studies were undertaken in strictly controlled situations rather than natural situations. Furthermore, because of their small sample sizes, these studies have had little precision regarding cost questions. This study was designed to evaluate the impact of a large-scale comprehensive intervention programme which included patient education and the monitoring of medications used in asthma treatment, according to the guidelines of the NHLBI. The primary goal of this study was to determine the economic impact of an asthma education programme from a third-party payer s perspective. The specific objectives of the study were: (i) to analyse and compare medical expenditures associated with asthma treatment (i.e. hospitalisation, emergency room visits and physician office visits, and drug expenditures) before and after the implementation of the asthma management programme; and (ii) to evaluate the impact of the asthma intervention programme on the frequency of usage of medical services by patients with asthma. Methods Study Design This prospective population-based study was designed to determine changes in resource utilisa-

3 Asthma Education Programme: Economic Impact 161 tion by identified patients with asthma. Claims data for all patients with asthma were analysed during the 9-month time period before the intervention (January 1997 to September 1997) and the 9-month time period after the implementation of the patient education programme (January 1998 to September 1998). The study period was limited to a 9-month time span following the study intervention due to lapsed time in which claims data were made available. Because the intervention programme started in September 1997, a 3-month wash-out period (October 1997 to December 1997) was incorporated to minimise any possible carry-over effect from the resource utilisation pattern during the preintervention phase. Patient Identification Because the study was population-based, the intervention programme was implemented to improve the treatment of asthma for the entire population. All of the participants in the study were members of a union health and welfare fund, located in the northeastern part of the US. The fund has members, both active and retired, who work or worked in the healthcare industry. Coverage of their medical and prescription benefits were provided with no copayment. Patients with asthma were identified using two criteria: (i) asthma medications in use; and (ii) the International Classification of Diseases (ICD-9) code for asthma (code 493) as their primary or secondary diagnosis, for at least 12 months prior to the time of intervention. Patients with asthma who agreed to participate in the asthma management educational intervention programme served as the intervention group. To compare the trends of treatment costs before and after the intervention in the study group to treatment costs incurred by patients not involved in the intervention programme, patients with asthma who did not receive any intervention were classified as the control group. Because the selected patients were treated as a cohort in order to follow their expenditures for 2 years (before and after the intervention period), an inclusion criterion required patients to maintain active membership of the union and welfare fund throughout the study period. Those patients who terminated their membership before the end of the study period were excluded because any medical services utilised after the termination of their membership would not be captured in the data set utilised for the study. Intervention Programme The asthma intervention programme was offered to improve the outcomes of patients with asthma through the following interventions: (i) therapy management interventions with physicians to ensure that patients were using the most appropriate medications through drug utilisation review measures; (ii) mailing of written educational materials providing information on asthma management; (iii) communication with physicians in order to improve compliance with the NHLBI prescription practice guidelines for asthma; and (iv) compliance intervention programmes that included direct communication with the patient, if necessary. Drug utilisation reviews were conducted to ensure appropriate medication prescribing and to encourage patient compliance. By analysing claims data and assessing the frequency of prescription refills, it could be determined when intervention group patients either overutilised short term medication without long term controller medication, or were noncompliant with long term controller medication with or without the use of short term medication. These behaviours were identified by investigators and physicians were notified by mail so that appropriate interventions could be initiated and compliance with proper drug regimens encouraged. If deemed necessary, physicians and/or patients were subsequently contacted by an investigator to discuss potential or unresolved problems. Educational materials were sent simultaneously, in addition to the information on drug utilisation, to patients in the intervention group every 3 months for the duration of the study (1 year; includes the washout period). The first set of educational materials were designed to help patients with asthma better understand a few of the most commonly used

4 162 Suh et al. asthma medications, the steps for appropriate inhaler use and the use of a spacer. The second set of materials were designed to enable patients to recognise when their asthma attacks are under poor control, inform them of the early warning signals of an asthma attack and aid them in understanding the physiological processes that occur during asthma and allergy attacks. The third educational piece provided information that encouraged adherence to medications, even when the allergy season is over. The fourth educational piece provided tips to parents of children with asthma on what they can do to prevent their children from having attacks at school. It also discussed the effects asthma and asthma medications can have on a child s education and on a parent s work. Statistical Analysis All claims data for hospitalisation, emergency room visits, physician office visits and drug costs were merged using the patients identification numbers and dates of birth, and then analysed to determine any statistical differences before and after implementation of the educational programme. A panel of 5 pharmacists reviewed all of the medications received by the patients with asthma and classified these medications into asthma medication and nonasthma medication according to the ingredients and therapeutic classes. [22] Because this cohort study was prospectively designed, each patient served as his or her own control throughout the study period. Thus, the difference in treatment costs before and after the intervention was determined for each patient, and comparisons within groups were possible. Because the sample size was large, differences in outcome variables between the pre- and postintervention periods were tested using a paired t-test. [23,24] Chisquare statistics were used to test for differences in the frequencies of the use of medical services for the treatment of asthma before and after the intervention. When no significant interaction was found to exist between the groups and the study variables, an analysis of covariance was performed to determine between-group differences in treatment costs before and after the intervention. This was completed after adjusting for disparities in the treatment costs which occurred during the preintervention phase. [25,26] All of the analyses were conducted using SAS statistical software. [27] The nominal dollar values for 1998 were converted to 1997 constant dollars using the healthcare price index for emergency room, hospitalisation and physician visit costs, and the prescription drug price deflator for the asthma medications, in order to keep them comparable for both years. [28] Results Patient Characteristics Of the 5527 selected patients who met the inclusion criteria for the study, 2235 patients were included in the intervention group and 3292 patients served as the control group. The demographics for the intervention and control groups are presented in table I. The average age of the intervention and control populations was 30.8 and 32.2 years, respectively (p = 0.011). The total paediatric component (patients <15 years of age) made up 32.8% of the intervention group and 26.9% of the control group. Patients aged between 45 and 59 years accounted for about 25% of the patients in each group. The proportion of male and female patients in both groups was similar (41 and 59%, respectively; p = 0.214). Cost of Asthma Care The average asthma treatment cost per patient in the entire study population is depicted in figure 1. In the intervention group, treatment costs incurred during the 9-month study period decreased from an average of $US499 to an average of $US415 per patient (a 17% reduction; p = ) after the intervention. During the same period, total asthma treatment costs decreased from $US227 to $US217 per patient (a 4% reduction; p = ) in the control group. Total asthma treatment costs before and after the intervention differed signifi-

5 Asthma Education Programme: Economic Impact 163 Table I. Patient demographics Parameter Intervention group (n = 2235) Control group (n = 3292) Total (n = 5527) p Value [no.(%)] [no.(%)] [no.(%)] Age (years) mean ± SD 30.8 ± ± ± 19.5 < (32.8) 884 (26.9) 1618 (29.3) (13.0) 549 (16.7) 839 (15.2) (22.5) 760 (23.1) 1262 (22.8) (25.2) 882 (26.8) 1445 (26.1) (6.5) 217 (6.6) 363 (6.6) Gender male 938 (42.0) 1326 (40.3) 2264 (41.0) female 1297 (58.0) 1966 (59.7) 3263 (59.0) SD = standard deviation. cantly in the intervention group compared with the control group after adjusting for the differences in treatment costs which occurred during the preintervention phase (p = ). In the preintervention phase, asthma medications (34%) accounted for the greatest proportion of the average total treatment cost of $US499 for the intervention group, followed by hospitalisation (33%), physician visits (30%) and emergency room visits (3%) before the intervention. After the intervention, however, the relative contribution of hospitalisation costs was similar, but asthma drug costs increased to 40% of the total treatment cost of $US415, while costs attributed to physician office visits decreased to 23% of total costs. There were also slight changes in the distribution of costs in the control group during the study period. Hospitalisation costs accounted for approximately 35% of average total treatment costs and emergency room costs were close to 4% both before and after the intervention. The proportion of average total treatment costs for visits to a physician office decreased from 41 to 36% in the control group, but the proportion of costs incurred for asthma medications increased from 19 to 25% after the intervention. Costs for hospitalisation after implementation of the asthma intervention in the study group were not significantly different from those of the control group (p = ). However, hospitalisation costs before and after implementation of the asthma intervention in the study group were significantly different from those of the control group, after controlling for differences in treatment costs during the preintervention phase (p = ). Costs associated with emergency room visits in the study group decreased by 29% after the intervention, while costs in the control group decreased by 10% during the same period (p = 0.047). Figure 2 presents the distribution of average asthma treatment costs per patient in the intervention group, according to age, before and after the intervention. The figure shows 2 types of costs: total asthma treatment costs (represented by a bar graph) and asthma medication costs (represented by a line graph). Total asthma treatment costs include the costs of hospitalisation, emergency room visits, physician visits and medication, whereas asthma medication costs include only the cost of medications used to treat asthma. Therefore, the difference between total treatment costs and asthma medication costs indicates the medical costs associated with asthma treatment. In general, the total treatment cost per patient decreased across all age groups after the intervention, but the asthma medication costs did not decrease after the intervention, except for patients aged between 15 and 29 years. This is probably because the intervention programme encouraged physicians and patients to use agents according to the NHLBI guidelines. Paediatric patients (patients <15 years of age) constituted the largest proportion (32.8%) of the

6 164 Suh et al. Cost per patient ($US) Hospitalisation cost Emergency room cost Physician cost Asthma drug cost 0 Before After Before After Before After Intervention group Control group All participants Fig. 1. Average asthma treatment costs per patient before and after implementation of the asthma intervention programme. Costs were calculated based on all patients with asthma who participated in the study (n = 5527). study population, however, the total treatment cost per paediatric patient was the lowest before ($US379) and after the intervention ($US266) compared with other age groups (decrease of 29.8% after the intervention). Paediatric patients asthma medication costs accounted for 21.4% of total costs before the intervention and 28.2% after the intervention; these are the lowest proportions of total asthma treatment costs compared with the other age groups. In contrast, patients older than 60 years constituted the smallest proportion (6.5%) of the study population but incurred the highest total asthma treatment cost before ($US584) and after ($US560) the intervention (decrease of 4.1% after the intervention; smallest reduction of all age groups). More than half of the total asthma treatment cost incurred for patients in this age group before and after the intervention was accounted for by asthma medications ($US327 and $US328, respectively). Patients aged from 15 to 29 years showed the greatest (34.4%) reduction in total treatment costs after the intervention; costs decreased from an average of $US579 to an average of $US380 per patient. Asthma medication costs in this age group also decreased by 23.5% after the intervention. Similarly, total asthma treatment costs decreased by 18.8%inpatientsaged30to44yearsand10.6% inpatientsaged45to59years. Table II summarises the average costs incurred per user of each category of service (hospitalisation, emergency room visits, physician visits and asthma medications) during the study period. These costs were calculated based on the number of patients with asthma who utilised each service. Table II presents mean costs rather than median values, despite the large standard deviations, because mean values would be more informative to healthcare decision-makers or policy-makers. The average cost of hospitalisation decreased from $US4183 to $US3734 per patient in the intervention group (a 10.7% decrease; p = ), whereas it increased from $US3373 to $US3491 in the control group (a 3.5% increase; p = ). However, these differences are not statistically significant. The average costs of emergency room visits were very similar before and after the intervention in both the study and the control group. The average cost per user for a physician visit decreased significantly from $US153 to $US99 in the intervention group (a 35% decrease; p = ). The average physician cost per user in the control group also decreased from $US98 to $US84 (a 14% decrease; p = ).

7 Asthma Education Programme: Economic Impact 165 The cost of asthma medications averaged $US220 per user in the study group before the intervention andthenincreasedto$us239aftertheintervention. However, this increase was not statistically significant (p = ). The control group incurred a significant increase in asthma medication costs, increasing from an average of $US96 per patient to $US122 during the same period (p = ). The asthma medication costs calculated do not include medications that were administered during admission to the hospital or emergency room. Only asthma medications that were used on an outpatient basis were taken into account. Frequency of Medical Services Used Table III presents data on the utilisation of services by all of the patients 9 months before and after the intervention. The average length of stay in the hospital was very similar for both groups approximately 3.4 days before the initiation of the programme and 3.1 days after programme initiation. After the implementation of the intervention programme, the number of patients who were hospitalised on more than 1 occasion in the study group remained constant, but the number of patients who were hospitalised only once in the study group decreased from 80 to 76 (a 5% decrease; p = 0.749). In the control group, the number of patients who were hospitalised twice increased (by 12%; p = 0.109), whereas the number of patients who werehospitalisedoncedecreasedfrom73to61(a 16% decrease; p = 0.300) during the same period. The number of patients in the intervention group who visited the emergency room once before the intervention decreased significantly from 134 to 99 (a 26% reduction; p = 0.022), whereas this number in the control group decreased nonsignificantly from 165 to 153 (a 17% reduction; p = 0.501). The number of patients in the intervention group who visited the emergency room twice or less decreased from 167 before initiation of the programme to 119 after the programme initiation (a 29% reduction). However, the number of patients in the control group who visited the emergency room twice or less decreased only slightly from 179 to 172 (a 3.9% reduction). Overall, the total number of patients who visited the emergency room decreased 600 Total asthma treatment cost before intervention Total asthma treatment cost after intervention Asthma drug cost before intervention Asthma drug cost after intervention 500 Cost per patient ($US) <15 (n = 734) (n = 290) (n = 502) Patient age (years) (n = 563) 60 (n = 146) Fig. 2. Total asthma treatment costs and asthma medication costs per patient by age in the intervention group before and after implementation of the asthma education intervention programme. Costs are calculated based on all asthma patients who participated in the study (n = 2235).

8 166 Suh et al. Table II. Average asthma treatment costs ($US) by type of service before and after implementation of the asthma intervention programme Category of service Intervention group (n = 2235) [mean ± SD (no. of pts who utilised the service)] Control group (n = 3292) [mean ± SD (no. of pts who utilised the service)] before after p value before after p value Hospitalisation 4183 ± 5005 (88) 3734 ± 3530 (85) ± 3368 (78) 3491 ± 3162 (71) Emergency room 215 ± 165 (179) 217 ± 160 (131) ± 62 (185) 167 ± 57 (174) Physician visits 153 ± 227 (2192) 99 ± 170 (2152) ± 164 (3150) 84 ± 170 (3092) Asthma medication 220 ± 285 (1706) 239 ± 325 (1540) ± 228 (1461) 122 ± 275 (1457) pts = patients; SD = standard deviation. by 26.8% in the intervention group and by 5.9% in the control group. The number of patients who visited the physician twice or more decreased significantly (p < 0.05) in both the intervention and control groups, whereas the number of patients who visited the physician s office once increased significantly (p < 0.01) after the intervention in both groups. This may be because patients who visited the physician s office more than twice before the intervention visited once after the intervention. In the study group, 518 patients visited the physician s office 4 times or more before the intervention, and 309 patients visited 4 or more times after the intervention (a 40% decrease; p = 0.001). The number of patients in the control group who visited their physician very frequently (more than 4 visits during the 9- month period) also decreased from 342 to 286 (a 16% decrease; p = 0.025) during the study period. In reference to the utilisation of asthma medications, the number of patients who filled between 1 and 3 prescriptions during the 9-month period decreased by 8.9% (p = 0.096) in the intervention group and by 10.6% (p = 0.013) in the control group. The number of patients who obtained more than 4 but less than 9 prescriptions decreased significantly in the intervention group (p = 0.018); however, the number of patients in this category in the control group was increased, although the increase was statistically nonsignificant (p = 0.065). Table IV shows the average utilisation of medical services (number of hospitalisations, emergency room visits, physician visits and asthma medications) using the total number of patients in each group as the denominator. Although the average number of hospitalisations per member was reduced in both the intervention group by 8.5% (p = ) and the control group by 3.8% (p = ), neither reduction was statistically significant. The frequency of emergency room visits and physician visits was reduced significantly in the study group after the intervention, by 27% each (p = and p = , respectively). However, in the control group, the number of emergency room visits did not change significantly over the study period (p = ) but the frequency of visits to the physician decreased significantly (p=0.0001). The total number of asthma prescriptions filled significantly decreased by 6% (p = ) in the intervention group, but increased by 18% (p = ) in the control group. Discussion This population-based study conducted from a third-party payer s perspective demonstrated that an asthma educational programme resulted in a reduction in the use of acute health services and reduced total asthma treatment costs when the intervention guidelines were followed. During the 9-month period following implementation of the asthma education programme, the total asthma treatment costs per patient were reduced by 17% in theinterventiongroupandby4%inthecontrol group. There was a 9% reduction in the rate of hospital admissions, a 27% reduction in the occurrence of emergency room usage, a 27% reduction in the frequency of physician visits and a 6% reduction in the number of asthma prescriptions in the intervention group. Unlike most of the previous studies, [7,8,17,20,21] the inclusion of a control group al-

9 Asthma Education Programme: Economic Impact 167 lowed for cost comparisons between the intervention and control groups; however, differences in costs between the 2 groups existed prior to the intervention. The results of this study are consistent with the resultant cost savings of a variety of asthma-specific intervention programmes, demonstrating that intervention programmes can reduce asthma treatment costs by reducing hospitalisation and emergency room visits. [7,8,13-21] These programmes stressed the need for patient education, physician access and use of appropriate asthma medications. However, one study did argue that intensive patient education is not cost effective when compared with conventional patient education. [29] The present study found average asthma treatment costs to be approximately $US450 per asthma patient (in both groups) per year before the intervention, similar to that reported in previous studies. [7,21] This figure was projected from the average total treatment cost of $US338 during the 9-month pre-intervention period. The results also revealed that drug costs constituted the largest proportion of asthma treatment costs (34% of the total treatment cost before intervention, and 40% after intervention in the study group), followed by costs associated with hospitalisation and physician visits. The proportion of costs calculated in this study is similar to that in a previous study which documented that drug costs constituted 37%, hospital costs 20 to 35% and physician costs 22% of the total direct treatment costs for patients with mild to moderately severe asthma. [30] Because healthcare providers were encouraged in the present study to prescribe inhaled anti-inflammatory medications as part of the intervention programme, patient adherence to this intervention guideline may have contributed to the increase in asthma drug cost per user. Although the average asthma medication cost per user increased from $US220 to $US239, the asthma medication cost per patient decreased, most likely because the intervention programme attempted to discourage the use of unnecessary and inappropriate medications according to NHLBI guidelines. Table III. Number of patients who used the services for asthma treatment during the study period Intervention group (n = 2235) Control group (n = 3292) before after change (%) p value before after change (%) p value Hospitalisation length of stay (days) Mean ± SD 3.4 ± ± ± ± NA NA Emergency room visits NA NA Physician office visits Number of prescriptions NA = not applicable; SD = standard deviation.

10 168 Suh et al. Table IV. Frequency of medical services used per patient with asthma before and after implementation of the asthma education intervention programme (mean ± standard deviation) a Service Intervention group (n = 2235) Control group (n = 3292) before after p value before after p value No. of hospitalisations ± ± ± ± No. of emergency room visits ± ± ± ± No. of physician office visits ± ± ± ± No.ofprescriptionsfor asthma drugs ± ± ± ± a Utilisation is calculated by the ratio of patients who used each service to the number of patients who participated in this study. The results of this study revealed that paediatric patients incurred the lowest total cost when compared with other age groups over the study period. However, the asthma intervention programme seemed to be most effective in patients aged 15 to 29 years, resulting in a relatively large reduction (34%) in the total cost of treatment per patient after the intervention. Patients over the age of 60 years incurred the greatest medication cost compared with other age groups, and the intervention was least effective in reducing total costs, yielding only a 4.1% reduction in total treatment costs in this subgroup of patients. This may indicate that asthma educational programmes may not be equally efficacious across all age groups. The effect of asthma intervention on resource utilisation by different age groups has not been fully addressed yet and needs to be explored further. Whereas most previous studies have evaluated the impact of asthma educational programmes on small patient populations with severe asthma, or patients who are high utilisers of medical resources, our study analysed population-based asthma treatment costs. The inclusion of patients with various asthma severities mild, moderate and severe provides a complete picture of the effect of an intervention. Measuring cost reductions stemming only from high cost/high-utilising patients is inappropriate, because these patients will usually appear to incur much lower costs during the following year, with or without an asthma education programme. [7] Although careful consideration was used when designing this study, and a thorough analysis was performed to evaluate the applied methodology and resulting data, some limitations warrant discussion. The potential for selection bias existed because intervention group patients comprised respondents who volunteered themselves for participation in the asthma management programme. Owing to the characteristics of population-based study, patients were not randomly assigned to the intervention or control groups. It is anticipated that increased disease severity could influence a patient s willingness to participate in an asthma management programme in an attempt to minimise their asthma-related problems. This hypothesis could possibly explain the significantly higher total asthma treatment costs associated with the study group prior to intervention when compared with the control group. To overcome the inequities between the study and control group treatment costs before intervention, comparisons of each patient s treatment cost before and after intervention were performed. An additional limitation of this study was that intervention cost data were not collected; therefore, determining the economic effectiveness of the intervention was not possible. Results of the study should also be generalised with caution because the sample population was composed primarily of healthcare workers. Because of these limitations, further research is necessary to identify the factors influencing patient treatment costs. Although study patients received asthma education materials by mail sequentially every 3 months for a full year, this intervention may not have altered patients outcomes as drastically as an intensive asthma education programme might have. Futurestudyintoimplementinganintensiveprogramme is needed to evaluate the full effects on

11 Asthma Education Programme: Economic Impact 169 treatment costs and clinical outcomes. Additionally, a longer follow-up period after intervention is preferable to allow adequate time for practitioners and patients to adjust their behaviours and comply with the recommended guidelines. Claims data have the advantage of enabling analyses of global and longitudinal trends of an intervention programme, but the use of claims-based measures for population-based assessment has some limitations because some relevant information may be unavailable. [31] For example, patients may occasionally use their spouse s health or prescription insurance plan to obtain treatment. Unfortunately, there is no proper way to adjust for this usage bias with such a data set. Conclusions Intensive patient education and treatment management should be advocated to reduce treatment costs and improve outcomes in patients with asthma. This can be achieved with the implementation of an asthma education programme that follows the recommendations of the NHLBI guidelines. Acknowledgements Thisstudywasmadepossiblebyanunrestrictedgrant from National Prescription Administrators. The authors thank Dr Geoffrey Gibson, Ms Griselda Chapa, Mr David L. Brodsky and Dr Russell G. Jayne for providing the necessary data and acknowledge the helpful comments from Drs Willard G. Manning Jr, Kevin Lynn, Donald Woodward and Ijeoma Okpara. References 1. Adams PF, Marano MA. Current estimates from the National Health Interview Survey, Vital and health statistics series 10 (193). Hyattsville (MD): National Center for Health Statistics, Weiss KB, Gergen PJ, Hodgson TA. An economic evaluation of asthma in the United States. N Engl J Med 1992; 326 (13): Mushinski M. Average hospital charges for asthma treatment: United States Stat Bull 1997; Apr-Jun: National Heart Lung and Blood Institute. 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12 170 Suh et al. 25. Howell DC. Statistical Methods for Psychology. 4th ed. Belmont (CA): Waldsworth Publishing Co., Kleinbaum DG, Kupper LL, Muller KE. Applied regression analysis and other multivariable methods. 2nd ed. Belmont (CA): Duxbury Press, SAS Institute Inc. SAS/STAT User s Guide, Version 6. Cary (NC): SAS Institute, Council of Economic Advisers. Economic report of the president. Washington, DC: U.S. Government Printing Office, Kauppinen R, Sintonen H, Tukiainen H. One-year economic evaluation of intensive vs conventional patient education and supervision for self-management of new asthmatic patients. Respir Med 1998; 92: Barnes PJ, Jonsson B, Klim JB. The costs of asthma. Eur Respir J 1996; 9: Birnbaum HG, Cremieux PY, Greenberg PE, et al. Using healthcare claims data for outcomes research and pharmacoeconomic analyses. Pharmacoeconomics 1999; 16 (1): 1-8 About the Authors: Dong-Churl Suh, M.B.A., Ph.D., is an Assistant Professor at Rutgers University College of Pharmacy, Piscataway, New Jersey, USA. Dr Suh conducted numerous research projects on pharmaceutical economics (including pharmacoeconomics) and management as well as outcomes assessment. He has also participated in many international quality-of-life study projects. Correspondence and offprints: Dr Dong-Churl Suh, College of Pharmacy, Rutgers-The State University of New Jersey, 160 Frelinghuysen Road, Piscataway, NJ 08854, USA. dush@rci.rutgers.edu