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(Correcting) misdiagnoses of asthma: a cost effectiveness analysis.

Pakhale S, Sumner A, Coyle D, Vandemheen K, Aaron S - BMC Pulm Med (2011)

Bottom Line: Economic analysis was performed to estimate the incremental lifetime costs associated with secondary screening of previously diagnosed asthmatic subjects.Analysis was from the perspective of the Canadian healthcare system and is reported in Canadian dollars.Cost savings primarily resulted from lifetime costs of medication use averted in those who had been misdiagnosed.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Ottawa, and The Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada. spakhale@ohri.ca

ABSTRACT

Background: The prevalence of physician-diagnosed-asthma has risen over the past three decades and misdiagnosis of asthma is potentially common.

Objective: to determine whether a secondary-screening-program to establish a correct diagnosis of asthma in those who report a physician diagnosis of asthma is cost effective.

Method: Randomly selected physician-diagnosed-asthmatic subjects from 8 Canadian cities were studied with an extensive diagnostic algorithm to rule-in, or rule-out, a correct diagnosis of asthma. Subjects in whom the diagnosis of asthma was excluded were followed up for 6-months and data on asthma medications and heath care utilization was obtained. Economic analysis was performed to estimate the incremental lifetime costs associated with secondary screening of previously diagnosed asthmatic subjects. Analysis was from the perspective of the Canadian healthcare system and is reported in Canadian dollars.

Results: Of 540 randomly selected patients with physician diagnosed asthma 150 (28%; 95%CI 19-37%) did not have asthma when objectively studied. 71% of these misdiagnosed patients were on some asthma medications. Incorporating the incremental cost of secondary-screening for the diagnosis of asthma, we found that the average cost savings per 100 individuals screened was $35,141 (95%CI $4,588-$69,278).

Conclusion: Cost savings primarily resulted from lifetime costs of medication use averted in those who had been misdiagnosed.

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Years since diagnosis of asthma and probability of being on asthma medication.
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Figure 2: Years since diagnosis of asthma and probability of being on asthma medication.

Mentions: Those determined not to be asthmatic were followed up prospectively for six months after the conclusion of the diagnostic screening. Resource use that could be associated with asthma care was monitored and was considered an incremental cost associated with the diagnostic screening. For those in whom asthma was ruled out by our diagnostic algorithm, and who were on medication prior to diagnostic screening we estimated the lifetime costs of medication use avoided as a result of the diagnostic screening. This required a four step approach. First, from the longitudinal study we estimated the probability that non asthmatics would be on medication in the year after the diagnosis of asthma using methodology congruent to survival analysis. (figure 2). For the 20 individuals (3.7%) for whom information on the year of diagnosis was missing we used the average years since diagnosis for each group. Secondly, we estimated the cost of medication by year since diagnosis for those in whom asthma was ruled out. This was estimated through linear regression analysis using data from the longitudinal study to adjust for increase in costs of annual medication based on year of diagnosis. Thirdly, we estimated the discounted lifetime cost associated with asthmatic medication for subjects in whom the diagnosis of asthma was ruled out by our diagnostic algorithm (figure 3). The discounted lifetime cost was the product of the probability of being on medication, the cost of medication and the discount factor, for each subsequent year. Finally we allocated the lifetime cost of medication based on the specific year since diagnosis for each subject who had been taking asthma medication, in whom the diagnosis of asthma was eventually ruled out by our testing algorithm.


(Correcting) misdiagnoses of asthma: a cost effectiveness analysis.

Pakhale S, Sumner A, Coyle D, Vandemheen K, Aaron S - BMC Pulm Med (2011)

Years since diagnosis of asthma and probability of being on asthma medication.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3118954&req=5

Figure 2: Years since diagnosis of asthma and probability of being on asthma medication.
Mentions: Those determined not to be asthmatic were followed up prospectively for six months after the conclusion of the diagnostic screening. Resource use that could be associated with asthma care was monitored and was considered an incremental cost associated with the diagnostic screening. For those in whom asthma was ruled out by our diagnostic algorithm, and who were on medication prior to diagnostic screening we estimated the lifetime costs of medication use avoided as a result of the diagnostic screening. This required a four step approach. First, from the longitudinal study we estimated the probability that non asthmatics would be on medication in the year after the diagnosis of asthma using methodology congruent to survival analysis. (figure 2). For the 20 individuals (3.7%) for whom information on the year of diagnosis was missing we used the average years since diagnosis for each group. Secondly, we estimated the cost of medication by year since diagnosis for those in whom asthma was ruled out. This was estimated through linear regression analysis using data from the longitudinal study to adjust for increase in costs of annual medication based on year of diagnosis. Thirdly, we estimated the discounted lifetime cost associated with asthmatic medication for subjects in whom the diagnosis of asthma was ruled out by our diagnostic algorithm (figure 3). The discounted lifetime cost was the product of the probability of being on medication, the cost of medication and the discount factor, for each subsequent year. Finally we allocated the lifetime cost of medication based on the specific year since diagnosis for each subject who had been taking asthma medication, in whom the diagnosis of asthma was eventually ruled out by our testing algorithm.

Bottom Line: Economic analysis was performed to estimate the incremental lifetime costs associated with secondary screening of previously diagnosed asthmatic subjects.Analysis was from the perspective of the Canadian healthcare system and is reported in Canadian dollars.Cost savings primarily resulted from lifetime costs of medication use averted in those who had been misdiagnosed.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Ottawa, and The Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada. spakhale@ohri.ca

ABSTRACT

Background: The prevalence of physician-diagnosed-asthma has risen over the past three decades and misdiagnosis of asthma is potentially common.

Objective: to determine whether a secondary-screening-program to establish a correct diagnosis of asthma in those who report a physician diagnosis of asthma is cost effective.

Method: Randomly selected physician-diagnosed-asthmatic subjects from 8 Canadian cities were studied with an extensive diagnostic algorithm to rule-in, or rule-out, a correct diagnosis of asthma. Subjects in whom the diagnosis of asthma was excluded were followed up for 6-months and data on asthma medications and heath care utilization was obtained. Economic analysis was performed to estimate the incremental lifetime costs associated with secondary screening of previously diagnosed asthmatic subjects. Analysis was from the perspective of the Canadian healthcare system and is reported in Canadian dollars.

Results: Of 540 randomly selected patients with physician diagnosed asthma 150 (28%; 95%CI 19-37%) did not have asthma when objectively studied. 71% of these misdiagnosed patients were on some asthma medications. Incorporating the incremental cost of secondary-screening for the diagnosis of asthma, we found that the average cost savings per 100 individuals screened was $35,141 (95%CI $4,588-$69,278).

Conclusion: Cost savings primarily resulted from lifetime costs of medication use averted in those who had been misdiagnosed.

Show MeSH
Related in: MedlinePlus