Correspondence Bothun et al.; Infant aphakic treatment study group: One-year strabismus outcomes in the Infant Aphakia Treatment Study (Ophthalmology 2013;120:1227e31) Dear Editor: We read with great interest the published reports of the Infant Aphakia Treatment Study Group.1 We would like to congratulate the authors for conducting such a study, which will guide us to the optimal surgical management and best method for optical rehabilitation for infants with monocular cataracts. It is important to compare the 2 treatment options and analyze multiple factors in this group of patients. However, we would like to seek a clarification regarding prevalence of strabismus in the study group by 12 months after cataract surgery. We would like to draw attention to articles by Bothun et al1 and Lambert et al.2 According to these 2 reports, the prevalence of strabismus in the same study group was postulated in different ratios. Lambert et al2 reported that 58% of patients in the intraocular lens group and 38% of patients in the contact lens group were orthotropic at the 12-month examination. Correspondingly, for the same study group, Bothun et al1 reported that 66.7% of patients in the intraocular lens group and 74.5% of patients in the contact lens group were strabismic (33.3% and 25.5% orthotropic, respectively) at the 12-month examination. We think that this discrepancy needs to be clarified by the authors.
ELIF Demirkılınç BILER, MD ONDER URETMEN, MD Department of Ophthalmology, Faculty of Medicine, Ege University, Izmir, Turkey
References 1. Bothun ED, Cleveland J, Lynn MJ, et al; Infant Aphakic Treatment Study Group. One-year strabismus outcomes in the Infant Aphakia Treatment Study. Ophthalmology 2013;120: 1227–31. 2. Lambert SR, Buckley EG, Drews-Botsch C, et al. Infant Aphakic Treatment Study Group. A randomized clinical trial comparing contact lens with intraocular lens correction of monocular aphakia during infancy: grating acuity and adverse events at age 1 year. Arch Ophthalmol 2010;128:810–8.
during those 12 months using a life-table approach. Once a patient was found to have strabismus, their status did not change. That is why in Figure 1 of the paper the percent of patients with strabismus increases at each follow-up visit until the 12 month visit when the results quoted by Biler and Uretmen are obtained: 66.7% for the intraocular lens (IOL) group and 74.5% for the contact lens (CL) group. In contrast, in the paper by Lambert et al2,3 that reported that the percent of patients that were orthotropic at 12 months was 58% for the IOL group and 38% for the CL group (that is, 42% and 62% with strabismus, respectively) only the measurements from the single follow-up visit at 12 months after surgery were considered. Thus, the results in the 2 papers are not strictly comparable because the methods used were different. We noted that a patient’s alignment could vary at different follow-up visits and hope that these different methods for presenting the results will inform the physicians who care for these patients.
ERICK D. BOTHUN, MD1 MICHAEL J. LYNN, MS2 SCOTT R. LAMBERT, MD3 1
Department of Ophthalmology, University of Minnesota, Minneapolis, Minnesota; 2Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia; 3 Department of Ophthalmology, Emory University, Atlanta, Georgia
References 1. Bothun ED, Cleveland J, Lynn MJ, et al; Infant Aphakic Treatment Study Group. One-year strabismus outcomes in the Infant Aphakia Treatment Study. Ophthalmology 2013;120: 1227–31. 2. Lambert SR, Buckley EG, Drews-Botsch C, et al; Infant Aphakia Treatment Study Group. A randomized clinical trial comparing contact lens with intraocular lens correction of monocular aphakia during infancy: grating acuity and adverse events at age 1 year. Arch Ophthalmol 2010;128:810–8. 3. Lambert SR, Lynn MJ, Hartmann EE, et al; The Infant Aphakia Treatment Study Group. Comparison of contact lens and intraocular lens correction of monocular aphakia during infancy: a randomized clinical trial of HOTV optotype acuity at age 4.5 years and clinical findings at age 5 years. JAMA Ophthalmol 2014 Mar 6.
Re: Abell et al.: Cost-effectiveness of femtosecond laser-assisted cataract surgery versus phacoemulsification cataract surgery (Ophthalmology
Author reply
2014;121:10-6)
Dear Editor: Thank you for the opportunity to clarify the strabismus results reported in the 2 papers from the Infant Aphakia Treatment Study. In the paper by Bothun et al,1 the strabismus results were reported using 2 different methods. In 1 method, the cumulative percent of patients developing strabismus during the first 12 months after surgery was calculated by considering all available follow-up visits
Dear Editor: We read with interest the recently published study by Abell et al,1 highlighting the economic issues of femtosecond laser-assisted cataract surgery (FCS). The authors used a decision tree model to estimate the cost effectiveness of FCS compared with phacoemulsification cataract surgery (PCS). They reported with transparency the way they elaborated the model and how they selected
e53
Ophthalmology Volume 121, Number 10, October 2014 probabilities, costs, and utility values. After a deterministic sensitivity analysis using optimistic and pessimistic scenarios, they concluded that FCS failed to reach the threshold of costeffectiveness, and that a reduction in the cost of FCS (including consumables) would increase the probability of FCS being cost effective. Cost-effectiveness analyses are conducted not only for assessing the cost effectiveness of innovations, but also to provide valid and precise estimates of cost and patient outcomes to help define appropriate fees. The model proposed by Abell et al was not designed to reach the latter objective. Complication rates after FCS are not well known and long-term visual outcomes, including visual performance stability or the incidence of posterior capsule opacification, are not considered in this model. The authors used unpublished data or data from heterogeneous population samples of FCS and PCS to populate their model. For utility values, which are a key parameter of the model, the authors used indirect estimates derived from visual acuity outcomes applying an unreferenced algorithm. When uncertainty exists on a model parameters value, it is recommended that a probabilistic sensitivity be conducted, preferably to a deterministic sensitivity analysis.2 Indeed, estimating the probability of FCS being cost effective compared with PCS in different scenarios would be extremely useful. Additionally, the authors used an estimated 5% improvement in the proportion of patients achieving a 6/12 visual acuity in the better eye. Although PCS is known to provide good visual and anatomic results, there is a difference observed between eyes having ocular comorbidities and the other eyes without ocular comorbidities. It is presumed that FCS improves visual results by better centration and positioning of the intraocular lens in the capsular bag and decreases complication rates by better intrasurgeon and intersurgeon reproducibility over PCS.3,4 Thus, if an improvement is anticipated with FCS, it should be more on the proportion of patients achieving a 6/9 or 6/6 visual acuity than a 6/12 visual acuity. The authors’ decision model thus may underestimate the effectiveness of FCS over PCS. Additionally, because the objective of decision making in health care is to improve the well-being of populations, cost-effectiveness results in ophthalmology should then analyze the overall utility of patients, considering both eyes, rather than visual acuity in the better eye only. We fully agree with Abell et al on the need for randomized, controlled trials with adequate sample sizes to provide valid and precise results on differences in costs, utility, complication rates, or spectacle independence between FCS and PCS. The Economic Evaluation of Femtosecond Laser Assisted Cataract Surgery (FEMCAT) study (NCT01982006) we are conducting aims to answer these important issues by comparing safety and efficacy of both operative techniques and estimating a costutility ratio in a prospective, multicenter, randomized, pragmatic clinical trial. This trial, funded by the French Ministry of Health, has been designed to fully estimate complication rates and complete visual results in both eyes by enrolling 2000 eyes. Quality-adjusted life-years will be directly assessed through the HUI3 questionnaire (health Utility Index) and medical/nonmedical costs (ambulatory and in hospital) will be estimated prospectively over a 1-year period. Prospectively and accurately comparing FCS and PCS might yield a precise and valid incremental cost-utility ratio, efficacy and safety estimates to elaborate an appropriate economic
e54
model for this innovation. Such a trial may provide important answers to physicians, institutions, and companies.
CEDRIC SCHWEITZER, MD NATHALIE HAYES, MSC ANTOINE BREZIN, MD, PHD BEATRICE COCHENER, MD, PHD PHILIPPE DENIS, MD, PHD PIERRE-JEAN PISELLA, MD, PHD ANTOINE BENARD, MD, PHD, FOR THE FEMCAT
STUDY
GROUP
Financial Disclosure(s): FEMCAT “impact Médico-Economique de la chirurgie de la CAtaracte au laser Femtoseconde,” [Economic Evaluation of Femtosecond Laser Assisted Cataract Surgery] CHU de Bordeaux, supported by a grant from the French ministry of health (PSTIC 2012). clinical trial identifier: NCT01982006.
References 1. Abell RG, Vote BJ. Cost-effectiveness of femtosecond laserassisted cataract surgery versus phacoemulsification cataract surgery. Ophthalmology 2014;121:10–6. 2. Briggs AH, Weinstein MC, Fenwick EA, et al. ISPOR SMDM Modeling Good Research Practices Task Force. Model parameter estimation and uncertainty analysis: a report of the ISPORSMDM Modeling Good Research Practices Task Force Working Group-6. Med Decis Making 2012;32:722–32. 3. Filkorn T, Kovács I, Takács A, et al. Comparison of IOL power calculation and refractive outcome after laser refractive cataract surgery with a femtosecond laser versus conventional phacoemulsification. J Refract Surg 2012;28:540–4. 4. Roberts TV, Lawless M, Bali SJ, et al. Surgical outcomes and safety of femtosecond laser cataract surgery: a prospective study of 1500 consecutive cases. Ophthalmology 2013;120:227–33.
Author reply Dear Editor: We thank Dr Schweitzer and the Economic Evaluation of Femtosecond Laser Assisted Cataract Surgery (FEMCAT) study group for their interest in our paper.1 We concur that there will always be limitations with cost-effectiveness analyses (CEA) performed in an hypothetical fashion. Nonetheless, our modeling provides useful interpretation of best case and worst case CEA for femtosecond laser pretreatment to cataract surgery (LCS) through calculation of incremental cost effectiveness ratio cost per quality-adjusted lifeyear (QALY) gained. We agree that long-term data and outcomes of LCS remain unknown, as does any certainty of benefit of LCS over phacoemulsification cataract surgery (PCS). However, we have utilized benchmark CEA for PCS based on existing established outcomes (which include long-term visual stability and posterior capsular opacity). Our modeling has therefore been performed for outcomes everywhere between our existing gold standard PCS outcomes (0.978) and perfect outcomes (1.0). We demonstrated that, even if LCS demonstrates an ability to achieve perfect outcomes, at current cost to patient the technology does not meet established cost-effectiveness standards. Of note, we have not utilized hypothetical fees, but have used real pricing (as cost to patient), and this has been at a conservative level (often LCS costs more and therefore would be considered less cost effective than our modeling would suggest).
ELIF Demirkılınç BILER, MD ONDER URETMEN, MD Department of Ophthalmology, Faculty of Medicine, Ege University, Izmir, Turkey
References 1. Bothun ED, Cleveland J, Lynn MJ, et al; Infant Aphakic Treatment Study Group. One-year strabismus outcomes in the Infant Aphakia Treatment Study. Ophthalmology 2013;120: 1227–31. 2. Lambert SR, Buckley EG, Drews-Botsch C, et al. Infant Aphakic Treatment Study Group. A randomized clinical trial comparing contact lens with intraocular lens correction of monocular aphakia during infancy: grating acuity and adverse events at age 1 year. Arch Ophthalmol 2010;128:810–8.
during those 12 months using a life-table approach. Once a patient was found to have strabismus, their status did not change. That is why in Figure 1 of the paper the percent of patients with strabismus increases at each follow-up visit until the 12 month visit when the results quoted by Biler and Uretmen are obtained: 66.7% for the intraocular lens (IOL) group and 74.5% for the contact lens (CL) group. In contrast, in the paper by Lambert et al2,3 that reported that the percent of patients that were orthotropic at 12 months was 58% for the IOL group and 38% for the CL group (that is, 42% and 62% with strabismus, respectively) only the measurements from the single follow-up visit at 12 months after surgery were considered. Thus, the results in the 2 papers are not strictly comparable because the methods used were different. We noted that a patient’s alignment could vary at different follow-up visits and hope that these different methods for presenting the results will inform the physicians who care for these patients.
ERICK D. BOTHUN, MD1 MICHAEL J. LYNN, MS2 SCOTT R. LAMBERT, MD3 1
Department of Ophthalmology, University of Minnesota, Minneapolis, Minnesota; 2Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia; 3 Department of Ophthalmology, Emory University, Atlanta, Georgia
References 1. Bothun ED, Cleveland J, Lynn MJ, et al; Infant Aphakic Treatment Study Group. One-year strabismus outcomes in the Infant Aphakia Treatment Study. Ophthalmology 2013;120: 1227–31. 2. Lambert SR, Buckley EG, Drews-Botsch C, et al; Infant Aphakia Treatment Study Group. A randomized clinical trial comparing contact lens with intraocular lens correction of monocular aphakia during infancy: grating acuity and adverse events at age 1 year. Arch Ophthalmol 2010;128:810–8. 3. Lambert SR, Lynn MJ, Hartmann EE, et al; The Infant Aphakia Treatment Study Group. Comparison of contact lens and intraocular lens correction of monocular aphakia during infancy: a randomized clinical trial of HOTV optotype acuity at age 4.5 years and clinical findings at age 5 years. JAMA Ophthalmol 2014 Mar 6.
Re: Abell et al.: Cost-effectiveness of femtosecond laser-assisted cataract surgery versus phacoemulsification cataract surgery (Ophthalmology
Author reply
2014;121:10-6)
Dear Editor: Thank you for the opportunity to clarify the strabismus results reported in the 2 papers from the Infant Aphakia Treatment Study. In the paper by Bothun et al,1 the strabismus results were reported using 2 different methods. In 1 method, the cumulative percent of patients developing strabismus during the first 12 months after surgery was calculated by considering all available follow-up visits
Dear Editor: We read with interest the recently published study by Abell et al,1 highlighting the economic issues of femtosecond laser-assisted cataract surgery (FCS). The authors used a decision tree model to estimate the cost effectiveness of FCS compared with phacoemulsification cataract surgery (PCS). They reported with transparency the way they elaborated the model and how they selected
e53
Ophthalmology Volume 121, Number 10, October 2014 probabilities, costs, and utility values. After a deterministic sensitivity analysis using optimistic and pessimistic scenarios, they concluded that FCS failed to reach the threshold of costeffectiveness, and that a reduction in the cost of FCS (including consumables) would increase the probability of FCS being cost effective. Cost-effectiveness analyses are conducted not only for assessing the cost effectiveness of innovations, but also to provide valid and precise estimates of cost and patient outcomes to help define appropriate fees. The model proposed by Abell et al was not designed to reach the latter objective. Complication rates after FCS are not well known and long-term visual outcomes, including visual performance stability or the incidence of posterior capsule opacification, are not considered in this model. The authors used unpublished data or data from heterogeneous population samples of FCS and PCS to populate their model. For utility values, which are a key parameter of the model, the authors used indirect estimates derived from visual acuity outcomes applying an unreferenced algorithm. When uncertainty exists on a model parameters value, it is recommended that a probabilistic sensitivity be conducted, preferably to a deterministic sensitivity analysis.2 Indeed, estimating the probability of FCS being cost effective compared with PCS in different scenarios would be extremely useful. Additionally, the authors used an estimated 5% improvement in the proportion of patients achieving a 6/12 visual acuity in the better eye. Although PCS is known to provide good visual and anatomic results, there is a difference observed between eyes having ocular comorbidities and the other eyes without ocular comorbidities. It is presumed that FCS improves visual results by better centration and positioning of the intraocular lens in the capsular bag and decreases complication rates by better intrasurgeon and intersurgeon reproducibility over PCS.3,4 Thus, if an improvement is anticipated with FCS, it should be more on the proportion of patients achieving a 6/9 or 6/6 visual acuity than a 6/12 visual acuity. The authors’ decision model thus may underestimate the effectiveness of FCS over PCS. Additionally, because the objective of decision making in health care is to improve the well-being of populations, cost-effectiveness results in ophthalmology should then analyze the overall utility of patients, considering both eyes, rather than visual acuity in the better eye only. We fully agree with Abell et al on the need for randomized, controlled trials with adequate sample sizes to provide valid and precise results on differences in costs, utility, complication rates, or spectacle independence between FCS and PCS. The Economic Evaluation of Femtosecond Laser Assisted Cataract Surgery (FEMCAT) study (NCT01982006) we are conducting aims to answer these important issues by comparing safety and efficacy of both operative techniques and estimating a costutility ratio in a prospective, multicenter, randomized, pragmatic clinical trial. This trial, funded by the French Ministry of Health, has been designed to fully estimate complication rates and complete visual results in both eyes by enrolling 2000 eyes. Quality-adjusted life-years will be directly assessed through the HUI3 questionnaire (health Utility Index) and medical/nonmedical costs (ambulatory and in hospital) will be estimated prospectively over a 1-year period. Prospectively and accurately comparing FCS and PCS might yield a precise and valid incremental cost-utility ratio, efficacy and safety estimates to elaborate an appropriate economic
e54
model for this innovation. Such a trial may provide important answers to physicians, institutions, and companies.
CEDRIC SCHWEITZER, MD NATHALIE HAYES, MSC ANTOINE BREZIN, MD, PHD BEATRICE COCHENER, MD, PHD PHILIPPE DENIS, MD, PHD PIERRE-JEAN PISELLA, MD, PHD ANTOINE BENARD, MD, PHD, FOR THE FEMCAT
STUDY
GROUP
Financial Disclosure(s): FEMCAT “impact Médico-Economique de la chirurgie de la CAtaracte au laser Femtoseconde,” [Economic Evaluation of Femtosecond Laser Assisted Cataract Surgery] CHU de Bordeaux, supported by a grant from the French ministry of health (PSTIC 2012). clinical trial identifier: NCT01982006.
References 1. Abell RG, Vote BJ. Cost-effectiveness of femtosecond laserassisted cataract surgery versus phacoemulsification cataract surgery. Ophthalmology 2014;121:10–6. 2. Briggs AH, Weinstein MC, Fenwick EA, et al. ISPOR SMDM Modeling Good Research Practices Task Force. Model parameter estimation and uncertainty analysis: a report of the ISPORSMDM Modeling Good Research Practices Task Force Working Group-6. Med Decis Making 2012;32:722–32. 3. Filkorn T, Kovács I, Takács A, et al. Comparison of IOL power calculation and refractive outcome after laser refractive cataract surgery with a femtosecond laser versus conventional phacoemulsification. J Refract Surg 2012;28:540–4. 4. Roberts TV, Lawless M, Bali SJ, et al. Surgical outcomes and safety of femtosecond laser cataract surgery: a prospective study of 1500 consecutive cases. Ophthalmology 2013;120:227–33.
Author reply Dear Editor: We thank Dr Schweitzer and the Economic Evaluation of Femtosecond Laser Assisted Cataract Surgery (FEMCAT) study group for their interest in our paper.1 We concur that there will always be limitations with cost-effectiveness analyses (CEA) performed in an hypothetical fashion. Nonetheless, our modeling provides useful interpretation of best case and worst case CEA for femtosecond laser pretreatment to cataract surgery (LCS) through calculation of incremental cost effectiveness ratio cost per quality-adjusted lifeyear (QALY) gained. We agree that long-term data and outcomes of LCS remain unknown, as does any certainty of benefit of LCS over phacoemulsification cataract surgery (PCS). However, we have utilized benchmark CEA for PCS based on existing established outcomes (which include long-term visual stability and posterior capsular opacity). Our modeling has therefore been performed for outcomes everywhere between our existing gold standard PCS outcomes (0.978) and perfect outcomes (1.0). We demonstrated that, even if LCS demonstrates an ability to achieve perfect outcomes, at current cost to patient the technology does not meet established cost-effectiveness standards. Of note, we have not utilized hypothetical fees, but have used real pricing (as cost to patient), and this has been at a conservative level (often LCS costs more and therefore would be considered less cost effective than our modeling would suggest).
