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1.  Predicting Inhaled Corticosteroid Response in Asthma with Two Associated SNPs 
The pharmacogenomics journal  2012;13(4):306-311.
Inhaled corticosteroids are the most commonly used controller medications prescribed for asthma. Two single-nucleotide polymorphisms (SNPs), rs1876828 in CRHR1 and rs37973 in GLCCI1, have previously been associated with corticosteroid efficacy. We studied data from four existing clinical trials of asthmatics who received inhaled corticosteroids and had lung function measured by forced expiratory volume in one second (FEV1) before and after the period of such treatment. We combined the two SNPs rs37973 and rs1876828 into a predictive test of FEV1 change using a Bayesian model, which identified patients with good or poor steroid response (highest or lowest quartile, respectively) with predictive performance of 65.7% (p = 0.039 vs. random) area under the receiver-operator characteristic curve in the training population and 65.9% (p = 0.025 vs. random) in the test population. These findings show that two genetic variants can be combined into a predictive test that achieves similar accuracy and superior replicability compared with single SNP predictors.
doi:10.1038/tpj.2012.15
PMCID: PMC3434304  PMID: 22641026
Pharmacogenetics; Asthma; Glucocorticoids; Predictive Modeling
2.  Cost-effectiveness of omalizumab in adults with severe asthma: Results from the Asthma Policy Model 
Background
Omalizumab (trade name Xolair) is approved by the US Food and Drug Administration for treatment of moderate-to-severe allergic asthma. Given the high acquisition cost of omalizumab, its role and cost-effectiveness in disease management require definition.
Objective
We sought to identify the clinical and economic circumstances under which omalizumab might or might not be a cost-effective option by using a mathematic model.
Methods
We merged published data on clinical and economic outcomes (including acute event incidence, frequency/severity of hospitalizations, and health-related quality of life) to project 10-year costs, quality-adjusted life years (QALYs), and cost-effectiveness of treatment with omalizumab in addition to inhaled corticosteroids. Sensitivity analyses were conducted by using input data ranges from a variety of sources (published clinical trials and observational databases).
Results
For patients with baseline acute event rates, omalizumab conferred an additional 1.7 quality-adjusted months at an incremental cost of $131,000 over a 10-year planning horizon, implying a cost-effectiveness ratio of $821,000 per QALY gained. For patients with 5 times the baseline acute event rate, the cost-effectiveness ratio was $491,000 per QALY gained. The projected cost-effectiveness ratio could fall within a range of other programs that are widely considered to be cost-effective if the cost of omalizumab decreases to less than $200.
Conclusion
Omalizumab is not cost-effective for most patients with severe asthma. The projected cost-effectiveness ratios could fall within a favorable range if the cost of omalizumab decreases significantly.
Clinical implications
Based on the high cost of omalizumab, it is especially important that clinicians explore alternative medications for asthma before initiating omalizumab.
doi:10.1016/j.jaci.2007.07.055
PMCID: PMC3476046  PMID: 17904628
Omalizumab; cost-effectiveness; asthma; anti-IgE
3.  How Can We Communicate About Vaccines With Adolescents and Their Parents? 
Clinical pediatrics  2010;49(4):373-380.
Objective
To describe parents’ and adolescents’ perceptions about vaccination.
Methods
Qualitative interviews of 22 mothers/grandmothers and 25 10- to 14-year-olds.
Results
Themes emerged in 3 focus areas. (a) Understanding: Both adults and adolescents had difficulty understanding concepts of risks, benefits, prevention, and vaccination. (b) Decision making: Adults saw vaccination as an opportunity to help their adolescent develop skills for transition to adulthood. Adolescents worried about being lied to (reinforced by being told “it won’t hurt”), physical pain, and cleanliness. (c) Preventing sexually transmitted infections: Adults were divided between those who felt their child would not need such a vaccine and those who wanted to “be safe” to protect their child in the future.
Conclusions
At the same time that even basic concepts about vaccination should be explained to both adults and adolescents, adolescence represents a time for learning about responsible decision making. Discussion regarding the risks and benefits of vaccines can be part of transitioning to adult decision making.
doi:10.1177/0009922809351091
PMCID: PMC3773171  PMID: 20118100
4.  Propensity Score-based Sensitivity Analysis Method for Uncontrolled Confounding 
American Journal of Epidemiology  2011;174(3):345-353.
The authors developed a sensitivity analysis method to address the issue of uncontrolled confounding in observational studies. In this method, the authors use a 1-dimensional function of the propensity score, which they refer to as the sensitivity function (SF), to quantify the hidden bias due to unmeasured confounders. The propensity score is defined as the conditional probability of being treated given the measured covariates. Then the authors construct SF-corrected inverse-probability-weighted estimators to draw inference on the causal treatment effect. This approach allows analysts to conduct a comprehensive sensitivity analysis in a straightforward manner by varying sensitivity assumptions on both the functional form and the coefficients in the 1-dimensional SF. Furthermore, 1-dimensional continuous functions can be well approximated by low-order polynomial structures (e.g., linear, quadratic). Therefore, even if the imposed SF is practically certain to be incorrect, one can still hope to obtain valuable information on treatment effects by conducting a comprehensive sensitivity analysis using polynomial SFs with varying orders and coefficients. The authors demonstrate the new method by implementing it in an asthma study which evaluates the effect of clinician prescription patterns regarding inhaled corticosteroids for children with persistent asthma on selected clinical outcomes.
doi:10.1093/aje/kwr096
PMCID: PMC3202161  PMID: 21659349
confounding factors (epidemiology); inverse probability weighting; propensity score; sensitivity analysis; sensitivity function; uncontrolled confounding
5.  Genome-Wide Association Analysis in Asthma Subjects Identifies SPATS2L as a Novel Bronchodilator Response Gene 
PLoS Genetics  2012;8(7):e1002824.
Bronchodilator response (BDR) is an important asthma phenotype that measures reversibility of airway obstruction by comparing lung function (i.e. FEV1) before and after the administration of a short-acting β2-agonist, the most common rescue medications used for the treatment of asthma. BDR also serves as a test of β2-agonist efficacy. BDR is a complex trait that is partly under genetic control. A genome-wide association study (GWAS) of BDR, quantified as percent change in baseline FEV1 after administration of a β2-agonist, was performed with 1,644 non-Hispanic white asthmatic subjects from six drug clinical trials: CAMP, LOCCS, LODO, a medication trial conducted by Sepracor, CARE, and ACRN. Data for 469,884 single-nucleotide polymorphisms (SNPs) were used to measure the association of SNPs with BDR using a linear regression model, while adjusting for age, sex, and height. Replication of primary P-values was attempted in 501 white subjects from SARP and 550 white subjects from DAG. Experimental evidence supporting the top gene was obtained via siRNA knockdown and Western blotting analyses. The lowest overall combined P-value was 9.7E-07 for SNP rs295137, near the SPATS2L gene. Among subjects in the primary analysis, those with rs295137 TT genotype had a median BDR of 16.0 (IQR = [6.2, 32.4]), while those with CC or TC genotypes had a median BDR of 10.9 (IQR = [5.0, 22.2]). SPATS2L mRNA knockdown resulted in increased β2-adrenergic receptor levels. Our results suggest that SPATS2L may be an important regulator of β2-adrenergic receptor down-regulation and that there is promise in gaining a better understanding of the biological mechanisms of differential response to β2-agonists through GWAS.
Author Summary
Bronchodilator response (BDR) is an important asthma phenotype that measures reversibility of airway obstruction by comparing lung function before and after the administration of short-acting β2-agonists, common medications used for asthma treatment. We performed a genome-wide association study of BDR with 1,644 white asthmatic subjects from six drug clinical trials and attempted to replicate these findings in 1,051 white subjects from two independent cohorts. The most significant associated variant was near the SPATS2L gene. We knocked down SPATS2L mRNA in human airway smooth muscle cells and found that β2-adrenergic receptor levels increased, suggesting that SPATS2L may be a regulator of BDR. Our results highlight the promise of pursuing GWAS results that do not necessarily reach genome-wide significance and are an example of how results from pharmacogenetic GWAS can be studied functionally.
doi:10.1371/journal.pgen.1002824
PMCID: PMC3390407  PMID: 22792082
6.  Asthma-susceptibility variants identified using probands in case-control and family-based analyses 
BMC Medical Genetics  2010;11:122.
Background
Asthma is a chronic respiratory disease whose genetic basis has been explored for over two decades, most recently via genome-wide association studies. We sought to find asthma-susceptibility variants by using probands from a single population in both family-based and case-control association designs.
Methods
We used probands from the Childhood Asthma Management Program (CAMP) in two primary genome-wide association study designs: (1) probands were combined with publicly available population controls in a case-control design, and (2) probands and their parents were used in a family-based design. We followed a two-stage replication process utilizing three independent populations to validate our primary findings.
Results
We found that single nucleotide polymorphisms with similar case-control and family-based association results were more likely to replicate in the independent populations, than those with the smallest p-values in either the case-control or family-based design alone. The single nucleotide polymorphism that showed the strongest evidence for association to asthma was rs17572584, which replicated in 2/3 independent populations with an overall p-value among replication populations of 3.5E-05. This variant is near a gene that encodes an enzyme that has been implicated to act coordinately with modulators of Th2 cell differentiation and is expressed in human lung.
Conclusions
Our results suggest that using probands from family-based studies in case-control designs, and combining results of both family-based and case-control approaches, may be a way to augment our ability to find SNPs associated with asthma and other complex diseases.
doi:10.1186/1471-2350-11-122
PMCID: PMC2927535  PMID: 20698975
7.  Asthma self-assessment in a Medicaid population 
BMC Public Health  2009;9:244.
Background
Self-assessment of symptoms by patients with chronic conditions is an important element of disease management. A recent study in a commercially-insured population found that patients who received automated telephone calls for asthma self-assessment felt they benefitted from the calls. Few studies have evaluated the effectiveness of disease self-assessment in Medicaid populations. The goals of this study were to: (1) assess the feasibility of asthma self-assessment in a population predominantly insured by Medicaid, (2) study whether adding a gift card incentive increased completion of the self-assessment survey, and (3) evaluate how the self-assessment affected processes and outcomes of care.
Methods
We studied adults and children aged 4 years and older who were insured by a Medicaid-focused managed care organization (MCO) in a pre- and post-intervention study. During the pre-incentive period, patients with computerized utilization data that met specific criteria for problematic asthma control were mailed the Asthma Control Test (ACT), a self-assessment survey, and asked to return it to the MCO. During the intervention period, patients were offered a $20 gift card for returning the completed ACT to the MCO. To evaluate clinical outcomes, we used computerized claims data to assess the number of hospitalization visits and emergency department visits experienced in the 3 months after receiving the ACT. To evaluate whether the self-management intervention improved processes of care, we conducted telephone interviews with patients who returned or did not return the ACT by mail.
Results
During the pre-incentive period, 1183 patients were identified as having problems with asthma control; 25 (2.0%) of these returned the ACT to the MCO. In contrast, during the incentive period, 1612 patients were identified as having problems with asthma control and 87 (5.4%) of these returned the ACT to the MCO (p < 0.0001). Of all 95 ACTs that were returned, 87% had a score of 19 or less, which suggested poor asthma control.
During the 3 months after they received the ACT, patients who completed it had similar numbers of outpatient visits, emergency department visits, and hospitalizations for asthma as patients who did not complete the ACT. We completed interviews with 95 patients, including 28 who had completed the ACT and 67 who had not. Based on an ACT administered at the time of the interview, patients who had previously returned the ACT to the MCO had asthma control similar to those who had not (mean scores of 14.2 vs. 14.6, p = 0.70). Patients had similar rates of contacting their providers within the past 2 months whether they had completed the mailed ACT or not (71% vs. 76%, p = 0.57).
Conclusion
Mailing asthma self-assessment surveys to patients with poorly controlled asthma was not associated with better asthma-associated outcomes or processes of care in the Medicaid population studied. Adding a gift card incentive did not meaningfully increase response rates. Asthma disease management programs for Medicaid populations will most likely need to involve alternative strategies for engaging patients and their providers in managing their conditions.
doi:10.1186/1471-2458-9-244
PMCID: PMC2716341  PMID: 19607719

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