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1.  The Lifetime Economic Burden of Keratoconus: A Decision Analysis Using a Markov Model 
American journal of ophthalmology  2011;151(5):768-773.e2.
To estimate the expected incremental lifetime cost of treatment of keratoconus compared to the expected cost of the treatment of myopia.
Cost estimate from the patient’s perspective using a Markov decision model.
We modeled a hypothetical cohort of people with clinically significant incident keratoconus as defined by the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study. We included costs of clinic visits, fitting fees, contact lenses, surgical procedures, and complications. Survival curves of corneal transplants and associated complications were modeled using data from the 2007 Australian Graft Registry. Medical treatment regimens after surgery were defined by expert opinion.
The expected value of the lifetime cost of the treatment of keratoconus over myopia was $25 168 with a standard deviation of $16 247 and a median of $17 596. The factors that most influenced the lifetime cost were the probability of initial corneal transplant and a subsequent regraft. The cost of routine care had relatively little influence on the lifetime cost of care.
The expected lifetime cost of treatment of keratoconus represents a significant cost to patients and payors. While the cost of routine care for keratoconus is not trivial, the primary factor influencing changes in the cost of care for keratoconus is the probability of corneal transplant. Combined with the significantly impaired vision-related quality of life and the relatively young onset of disease, the economic burden of the treatment of keratoconus represents a significant public health concern.
PMCID: PMC4714341  PMID: 21310384
2.  Effect of Patient’s Life Expectancy on the Cost-effectiveness of Treatment for Ocular Hypertension 
Archives of ophthalmology  2010;128(5):613-618.
To measure the influence of age and/or expected lifespan in determining the cost-effectiveness of treating ocular hypertension to prevent primary open angle glaucoma.
A Markov model simulated the expected costs and benefits a cohort of people with ocular hypertension would accrue over their lifetime. The outcome of interest was the incremental cost effectiveness ratio. Data was taken from the Ocular Hypertension Treatment Study and public sources. The model was first tested for specific age cohorts to identify the influence of baseline age on the cost effectiveness cost-effectiveness of treatment. We then set each cohort’s life expectancy to determine the influence on cost effectiveness.
At a willingness to pay of greater than $75,000 treatment of people with a ≥ 2% annual risk of developing glaucoma was cost-effective for oeople 45 years of age, with a life expectancy of at least 18 years. However, to be cost-effective a person 55 years old must have a life expectancy of 21 years and someone age 65 must expect to live 23 years.
To meet most commonly accepted standards of cost-effectiveness, a person with ocular hypertension must have a life expectancy of at least 18 years to justify treatment at the ≥ 2% annual risk of glaucoma threshold. At higher levels of risk, a life expectancy of 7–10 years is required.
PMCID: PMC4010144  PMID: 20457984
3.  Longitudinal Trends in Resource Utilization in an Incident Cohort of Open Angle Glaucoma Patients 
American journal of ophthalmology  2012;154(3):452-459.e2.
To characterize the costs of caring for patients with open-angle glaucoma (OAG) in the United States (US) over time and to identify factors that influence these costs.
Longitudinal cohort study.
Claims data from 19,927 newly-diagnosed OAG patients enrolled in a large US managed care network were reviewed to identify glaucoma-related charges for all incident OAG patients from 2001–2009. Average glaucoma-related charges for enrollees with OAG were characterized in six month blocks from the date of initial OAG diagnosis through the following 5 years. Factors associated with being an enrollee in the costliest 5% for glaucoma-related charges (accruing ≥$5810 in charges in the first 2 years) were identified using logistic regression.
The costliest 5% of enrollees were responsible for $10,202,871 (24%) of all glaucoma-related charges. By comparison, those whose costs fell within the lower 50% of the cost distribution collectively amassed only $7,986,582 (19%) of all glaucoma-related charges. A spike in glaucoma-related charges occurred in the 6 month period around the time of OAG diagnosis, stabilized by 1 year following diagnosis, and remained relatively constant over time. Risk factors associated with being in the costliest 5% for glaucoma-related care included younger age, Northeastern US state residence, undergoing cataract surgery, and possessing ocular co-morbidities.(p<0.006 for all comparisons).
A small subset of enrollees account for a large proportion of all glaucoma-related charges. Understanding the characteristics of these individuals and finding ways to reduce disease burden and costs associated with their care can result in substantial cost savings.
PMCID: PMC3422396  PMID: 22789564
4.  The Development of a Decision Analytic Model of Changes in Mean Deviation in People with Glaucoma: The COA Model 
Ophthalmology  2012;119(7):1367-1374.
To create and validate a statistical model predicting progression of primary open angle glaucoma (POAG) assessed by loss of visual field as measured in mean deviation (MD) using three landmark studies of glaucoma progression and treatment.
A Markov decision analytic model using patient level data described longitudinal MD changes over seven years.
Patient level data from the Collaborative Initial Glaucoma Treatment Study (CIGTS, n=607), the Ocular Hypertension Treatment Study (OHTS, n=148, only those who developed POAG in the first five years of OHTS) and Advanced Glaucoma Intervention Study (AGIS, n=591), the COA model.
We developed a Markov model with transition matrices stratified by current MD, age, race and intraocular pressure categories and used a microsimulation approach to estimate change in MD over seven years. Internal validation compared model prediction for seven years to actual MD for COA participants. External validation used a cohort of glaucoma patients drawn from university clinical practices.
Main Outcome Measures
Change in visual field as measured in MD in decibels (dB).
Regressing the actual MD against the predicted produced an R2 of 0.68 for the right eye and 0.63 for the left. The model predicted ending MD for right eyes of 65% of participants and for 63% of left eyes within 3 dB of actual results at seven years. In external validation the model had an R2 of 0.79 in the right eye and 0.77 in the left at five years.
The COA model is a validated tool for clinicians, patients and health policy makers seeking to understand longitudinal changes in mean deviation in people with glaucoma..
PMCID: PMC3389134  PMID: 22537616
5.  High Resource Utilization Does Not Affect Mortality in Acute Respiratory Failure Patients Managed With Tracheostomy 
Respiratory care  2013;58(11):1863-1872.
Tracheostomy practice in patients with acute respiratory failure (ARF) varies greatly among institutions. This variability has the potential to be reflected in the resources expended providing care. In various healthcare environments, increased resource expenditure has been associated with a favorable effect on outcome.
To examine the association between institutional resource expenditure and mortality in ARF patients managed with tracheostomy.
We developed analytic models employing the University Health Systems Consortium (Oakbrook, Illinois) database. Administrative coding data were used to identify patients with the principal diagnosis of ARF, procedures, complications, post-discharge destination, and survival. Mean resource intensity of participating academic medical centers was determined using risk-adjusted estimates of costs. Mortality risk was determined using a multivariable approach that incorporated patient-level demographic and clinical variables and institution-level resource intensity.
We analyzed data from 44,124 ARF subjects, 4,776 (10.8%) of whom underwent tracheostomy. Compared to low-resource-intensity settings, treatment in high-resource-intensity academic medical centers was associated with increased risk of mortality (odds ratio 1.11, 95% CI 1.05–1.76), including those managed with tracheostomy (odds ratio high-resource-intensity academic medical center with tracheostomy 1.10, 95% CI 1.04 –1.17). We examined the relationship between complication development and outcome. While neither the profile nor number of complications accumulated differed comparing treatment environments (P > .05 for both), mortality for tracheostomy patients experiencing complications was greater in high-resource-intensity (95/313, 30.3%) versus low-resource-intensity (552/2,587, 21.3%) academic medical centers (P < .001).
We were unable to demonstrate a positive relationship between resource expenditure and outcome in ARF patients managed with tracheostomy.
PMCID: PMC4357268  PMID: 23650434
tracheostomy; acute respiratory failure; mechanical ventilation; critical illness; practice variation; quality assurance
6.  Demonstration of an online tool to assist managed care formulary evidence-based decision making: meta-analysis of topical prostaglandin analog efficacy 
The purpose of this paper was to demonstrate the use of an online service for conducting a systematic review and meta-analysis of the efficacy of topical prostaglandin analogs in reducing intraocular pressure (IOP) in glaucoma and ocular hypertension.
An online service provider (Doctor Evidence) reviewed and extracted data from the peer-reviewed literature through September 2009. Randomized controlled studies of at least three months’ duration assessing at least two prostaglandin analogs in patients with primary open-angle glaucoma, ocular hypertension, or normal-tension glaucoma were included. The primary endpoint was mean IOP. Summary estimates were created using random-effects models. The Q Chi-square test was used to assess statistical heterogeneity.
Sixteen studies satisfied the inclusion criteria and were analyzed. On average, greater IOP-lowering was seen with bimatoprost relative to latanoprost (1 mmHg, P = 0.025) and travoprost (0.8 mmHg, P = 0.033) based on mean IOP after 12–26 weeks of treatment. No statistical difference was observed in IOP-lowering between latanoprost and travoprost (P = 0.841). Findings were similar to previously published meta-analyses of topical prostaglandin analogs.
Systematic reviews relying on meta-analytic techniques to create summary statistics are considered to be the “gold standard” for synthesizing evidence to support clinical decision-making. However, the process is time-consuming, labor-intensive, and outside the capability of most formulary managers. We have demonstrated the effectiveness of a commercial service that facilitates the process of conducting such reviews.
PMCID: PMC3150474  PMID: 21845051
evidence-based medicine; meta-analysis; review; systematic; prostaglandin analogs; glaucoma
7.  Asymmetry in Keratoconus and Vision-Related Quality of Life 
Cornea  2013;32(3):267-272.
To examine the relation of increased ocular asymmetry over time on vision-related quality of life in keratoconus.
Subjects were in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study and had complete data on a least one scale of the NEI VFQ and examination data at baseline and at least one follow-up visit. Three measures of disease asymmetry (visual acuity, corneal curvature, and refractive error) and better eye status were assessed. Multilevel models were fit to the data.
Analyses were completed using 961 subjects. Six scales on the NEI VFQ had adequate variability to model (distance activity, driving, mental health, near activity, ocular pain, and role difficulties). Refractive error changes were not associated with statistically significant quality of life differences. Except for ocular pain, statistically significant, but not clinically meaningful, differences were found for visual acuity changes and corneal curvature changes. For a 0.1-unit logMAR visual acuity change, the quality of life scales decreased between 0.20 and 0.99 units. For a 1.00-D steepening of corneal curvature these decreases were on the order of 0.20 to 0.59 units. Changes related to asymmetry were small as well: decreases on the order of 0.20 to 0.38 units.
Increasing ocular asymmetry and decreases in visual acuity and corneal steepening in the better eye were associated with decreasing vision-related quality of life, though the magnitudes of the changes were not clinically meaningful. Of these two disease status indicators, the vision in the better eye had greater effect on vision-related quality of life.
PMCID: PMC3482277  PMID: 22825402
Keratoconus; quality of life; longitudinal
8.  Changes in the Quality of Life of People with Keratoconus 
American journal of ophthalmology  2008;145(4):611-617.
The Collaborative Longitudinal Evaluation of Keratoconus Study (CLEK) has previously shown that people with keratoconus report significantly impaired vision-related quality of life (V-QoL) as measured on the National Eye Institute Visual Function Questionnaire (NEI-VFQ), similar to people who have severe macular degeneration. In this report we evaluate changes that occurred in V-QoL over 7 years of follow-up.
Prospective cohort study of 1166 participants followed for 7 years.
We estimated change in quality of life by projecting the slope of a minimum of three reports on 11 scales of the NEI-VFQ. Correlation with clinical indicators was evaluated, and differences were assessed between those who had clinically significant changes in clinical factors and those who did not. Logistic regression was used to assess factors associated with a decline in 10 points or more in a scale score over 7 years.
All scales showed modest decline except Ocular Pain and Mental Health. Baseline factors were not associated with longitudinal change in NEI-VFQ scores. A 10-letter decline in high-contrast binocular visual acuity and a 3.00 D increase in corneal curvature were associated with significantly larger declines in V-QoL. In multivariate analysis, these factors also were found to be associated with a 10-point decline in NEI-VFQ scale scores.
Keratoconus is associated with significantly impaired V-QoL that continues to decline over time. For a substantial plurality these declines are significant.
PMCID: PMC2753249  PMID: 18226798
keratoconus; quality of life; NEI Visual Function Questionnaire; NEI-VFQ CLEK Study
10.  Pharmacogenetics of Complement Factor H (Y402H) and treatment of exudative age-related macular degeneration with ranibizumab 
To determine whether complement factor H (CFH) genotypes have a pharmacogenetic effect on the treatment of exudative age-related macular degeneration (AMD) with ranibizumab.
A retrospective study of 156 patients with exudative AMD treated with intravitreal ranibizumab monotherapy was conducted. AMD phenotypes were characterized by clinical examination, visual acuity, fundus photography, fluorescein angiography, and injection timing. Patients received intravitreal ranibizumab injections as part of routine ophthalmologic care and were followed for a minimum of nine months. Each patient was genotyped for the single nucleotide polymorphism rs1061170 (Y402H) in the CFH gene.
Baseline lesion size and angiographic type, as well as mean visual acuities at baseline, 6 months, and 9 months were similar among the three CFH genotypes. Over 9 months, patients with both risk alleles received approximately one more injection (p = 0.09). In a recurrent event analysis, patients homozygous for the CFH Y402H risk allele had a 37% significantly higher risk of requiring additional ranibizumab injections (p = 0.04)
In our cohort, response to treatment of AMD with ranibizumab differed according to CFH genotype, suggesting that determining patients' CFH genotype may be helpful in the future in tailoring treatment for exudative AMD with intravitreal ranibizumab.
PMCID: PMC3490485  PMID: 19091853
Complement Factor H; Ranibizumab; Age-Related Macular Degeneration; Pharmacogenetics
11.  Lens fluorescence and accommodative amplitude in pre-presbyopic and presbyopic subjects 
Experimental eye research  2007;84(5):1013-1017.
Accommodative amplitude (AA; the difference, measured in diopters, between the near and far points of vision) declines steadily with age such that, by midlife, most individuals are unable to focus clearly on near objects and, thus, are said to be presbyopic. Conversely, intrinsic lens fluorescence (LF) increases steadily with age. Previous studies have suggested that AA and LF are negatively correlated, independent of age. Were this to be the case, it might suggest that the biochemical modifications underlying increased tissue fluorescence (for example, glycation of lens proteins) contribute to presbyopia. We used quantitative techniques to re-evaluate the relationship between AA and LF in 161 healthy volunteers aged between 25 and 70. Our data confirmed that AA decreases with age, becoming essentially zero by age 55, and LF increases with age. However, in marked contrast to previous reports, statistical analysis failed to detect any correlation between LF and AA independent of age. Thus, the biochemical processes responsible for increased LF observed in the aged lens are unlikely to contribute directly to presbyopia.
PMCID: PMC2682368  PMID: 17359974
12.  Clinical phenotypes associated with the Complement Factor H Y402H variant in age-related macular degeneration 
American journal of ophthalmology  2007;144(3):404-408.
To determine whether the complement factor H (CFH) Y402H variant is associated with specific age-related macular degeneration (AMD) clinical phenotypes.
Retrospective, case-control study.
188 Caucasian subjects with AMD and 189 control subjects were genotyped for the T-to-C polymorphism in exon-9 of the CFH gene by restriction-fragment length analysis and DNA sequencing using genomic DNA from mouthwash samples. AMD phenotypes were characterized by clinical examination, fundus photography, and fluorescein angiography.
Heterozygosity for the at-risk genotype (TC) increased the likelihood for AMD 2.1-fold (95% CI 1.3–3.3) while homozygosity for the genotype (CC) increased the likelihood for AMD 6.5-fold (95% CI 3.4–12.5) in our population. The C allele was significantly associated with predominantly classic choroidal neovascularization (OR 2.01, 95% CI 1.34–3.30). Neovascular lesion size was similar among the three genotypes (p=0.67).
The Y402H CFH variant carried a significantly increased risk for developing AMD in our population. Genotype/phenotype correlations regarding choroidal neovascular lesion type were observed
PMCID: PMC2140051  PMID: 17631852

Results 1-12 (12)