A Value-Based Medicine cost-utility analysis of genetic testing for neovascular macular degeneration

Background There is a dearth of patient, preference-based cost-effectiveness analyses evaluating genetic testing for neovascular age-related macular degeneration (NVAMD). Methods A Value-Based Medicine, 12-year, combined-eye model, cost-utility analysis evaluated genetic testing of Category 3 AMD patients at age 65 for progression to NVAMD. The benefit of genetic testing was predicated upon the fact that early-treatment ranibizumab therapy (baseline vision 20/40–20/80) for NVAMD confers greater patient value than late-treatment (baseline vision ≤20/160). Published genetic data and MARINA Study ranibizumab therapy data were utilized in the analysis. Patient value (quality-of-life gain) and financial value (2012 US real dollar) outcomes were discounted at 3 % annually. Results Genetic testing-enabled, early-treatment ranibizumab therapy per patient conferred mean 20/40−1 vision, a 0.845 QALY gain and 14.1 % quality-of-life gain over sham therapy. Late-treatment ranibizumab therapy conferred mean 20/160+2 vision, a 0.250 QALY gain and 4.2 % quality-of-life gain over sham therapy. The gain from early-treatment over late-treatment was 0.595 QALY (10.0 % quality-of-life gain). The per-patient cost for genetic testing/closer monitoring was $2205 per screened person, $2.082 billion for the 944,000 estimated new Category 3 AMD patients annually. Genetic testing/monitoring costs per early-treatment patient totaled $66,180. Costs per early-treatment patient included: genetic testing costs: $66,180 + direct non-ophthalmic medical costs: −$40,914 + caregiver costs: −$172,443 + employment costs: −$14,098 = a net societal cost saving of $160,582 per early treatment patient. When genetic screening facilitated an incremental 12,965 (8.0 %) of the 161,754, new annual NVAMD patients aged ≥65 in the US to undergo early-treatment ranibizumab therapy, each additional patient treated accrued an overall, net financial gain for society of $160,582. Genetic screening was cost-effective, using World Health Organization criteria, when it enabled an incremental 4.1 % (6634) of 161,754 annual NVAMD patients ≥65 years to receive early-treatment ranibizumab therapy. Conclusions Genetic screening-enabled, early-treatment ranibizumab therapy for NVAMD is cost-effective if it enables an incremental 4.1 % of the annual US cohort of new-onset NVAMD patients ≥65 to undergo early-treatment with ranibizumab.


Open Access
*Correspondence: gary0514@gmail.com; gbrown@valuebasedmedicine.com 1 Center for Value-Based Medicine ® , 6010 West Mill Road, Flourtown, PA 19031, USA Full list of author information is available at the end of the article Several models predict the conversion of atrophic AMD to NVAMD, each using the Age Related Eye Diseases Study (AREDS) classification of AMD [4][5][6][7][8]. The more complex model in AREDS Report No. 17 [6], evaluated the eyes of 3212 participants, utilizing drusen severity and pigmentary abnormalities at baseline. The authors proposed a 9-step severity scale that combined a 6-step drusen area scale with a 5-step pigmentary abnormality scale. The 5-year risk of progression to advanced AMD varied from <1 % in Steps 1 and 2 to 43.5 % in Step 9 [6]. Nonetheless, the scale more accurately predicts central geographic atrophy (43.5 % in Step 9) than NVAMD (4.8 % in Step 9, but 21.1 % in the less severe Step 8) [6]. A simplified severity scale in AREDS Report No. 18 used large drusen and pigmentary changes in a 0-4 scale and demonstrated, when both were present bilaterally, the 5-year incidence of advanced AMD in at least one eye was 47.3 % [7]. While a top score of 4 identified 67.8 % of 5-year progressors to advanced AMD, it identified only 36.5 % progressing to NVAMD [7].
Blue Mountains Eye Study investigators [8], using an AREDS simplified severity scale, found a generalized estimating equation model showed 61.5 % of patients with bilateral drusen ≥125 μm and bilateral retinal pigment epithelial changes progressed to advanced AMD over 10 years. Assuming 70 % of those advanced AMD cases were neovascular [2], approximately 43 % of NVAMD cases would be identified. This converts to (57.0 % × 161,754 cases=) 92,200 new NVAMD patients aged ≥65 in the US not identified by phenotypic markers annually [1][2][3].
Considering the importance of earlier ranibizumab therapy, the authors undertook a Value-Based Medicine ® (VBM) [22][23][24], societal, cost-utility analysis to assess the patient preference-based, comparative effectiveness and cost-effectiveness (cost-utility) of genetic testing for NVAMD.

Methods
Features associated with genetic testing for NVAMD, and the economic modeling assumptions used are listed in Table 2. Comparative effectiveness quantified the incremental patient value gain (improvement in quality-of-life and/or length-of-life), though length-of-life change was not included, since better vision has not been well shown to lengthen life. Outcomes were measured in: (1) percent value gain, and (2) quality-adjusted life-year (QALY) gain [18,20,[22][23][24][25]. QALY gain was calculated by multiplying: (utility gain) × (years of interventional benefit). Financial metrics include: (1) cost-utility ratio, $/QALY, or dollars expended per QALY gained, associated with genetic testing-enabled, early-treatment ranibizumab for NVAMD, and (2) societal costs.

AMD demographics
The AREDS Research Group [5][6][7] defined four categories of AMD and showed oral supplements decrease the progression of Category 3 AMD (macular drusen ≥125 µm) to NVAMD, though not from Category 3 to central geographic atrophy. Yu and colleagues [4] refined the AREDS four-category model to a five-category model, separating AREDS [5][6][7] advanced AMD cases into central geographic atrophy (Category 4) and NVAMD (Category 5) in their genotypic/phenotypic study of AMD. Approximately 1.54 million people had NVAMD in the  High-risk = homozygous on all genetic loci for the alleles that increase the risk of advanced AMD Medium-risk = heterozygous on genetic loci for the alleles that increase/decrease the risk of advanced AMD Low-risk = homozygous on all genetic loci for alleles that decrease the risk of advanced AMD As per Yu et al. [4], all genes listed above are assumed to be tested for. This conservative assumption likely biases against the financial value gain and cost-effectiveness by increasing what will likely be decreased genetic costs in the future Progression to neovascular AMD Incremental, 10-year progression rate to neovascular AMD for Category 3 AMD patients with: a past smoking history, BMI of 25-29, normal fellow eye and greater than a high school education [4] Genetic profile

Neovascular AMD therapy
Clinical features, MARINA study [18,20,23] All participants had minimally classic or occult, subfoveal choroidal neovascularization The 0.5 mg ranibizumab dose was more effective than the 0.3 mg dose, and was thus the dose approved by the Food & Drug Administration and used in the current analysis [18] Treatment cohort (0.5 mg ranibizumab) mean vision: MARINA Study for years 1 and 2, then LOCF (last observation carried forward) of clinical trial data for years 3-12 [23] Eligible, MARINA sham cohort patients were treated with ranibizumab following the end of the randomized portion of the trial after 24 months. Thus, sham treatment, control cohort data utilized mean vision in the MARINA Study [18] for years 1 and 2, and a Lineweaver-Burke plot metaanalysis control cohort from six randomized, neovascular AMD clinical trials for years 3-12 of sham therapy [25] Adverse event disutility QALYs, a total of 0.045 QALY, were used to calculate adverse event QALYs subtracted from total patient value gain The average participant received 22 × 0.05 cc intravitreal injections, given approximately monthly, over 2 years Mean life expectancy: 12 years for the control and ranibizumab study cohorts [49]

Genetic profile 10-year progression Percent of progressors detected
Value-Based Medicine © , base case, cost-utility analysis parameters for the AMD genetic screening, cost-utility analysis [18,20,22,23] The patient value and financial value gains are those associated with genetic screening for neovascular AMD making possible the incremental earlier detection and earlier ranibizumab therapy for neovascular AMD Model timeline: 12 years = mean life expectancy for average neovascular AMD patient [18] Baseline vision in the early-treatment, ranibizumab therapy cohort was 20/40-20/80. Final vision outcome was 20/40 -1 [20] 20/40-1 vision in each eye equates with a utility of 0.789 [30,39] Baseline vision in the late-treatment, ranibizumab therapy cohort was 20/160-20/320. Final vision outcome was 20/160 +2 . [20] 20/160 +2 vision in each eye equates with a utility of 0.0.658 [29,30] Loss of vision in a first eye results in a utility loss of 0.0398 [35] The incremental cost-utility analysis per patient utilizes the incremental patient and incremental financial value gains associated with early-treatment ranibizumab therapy (baseline treatment vision 20/40-20/80) for neovascular AMD versus late-treatment ranibizumab therapy (baseline treatment vision of 20/160-20/320) [20] The costs of genetic screening were compared with the patient value gains and cost savings conferred by early-treatment ranibizumab therapy (versus late-treatment ranibizumab therapy) made possible by genetic screening The direct ophthalmic medical treatment costs were the same in the early-treatment, ranibizumab therapy and late-treatment, ranibizumab therapy cohorts, and therefore were not considered incremental costs Only Category 3 AMD eyes in patients who were 65 years of age were tested with genetic screening 22.5% of baseline Category 3 cases have a high-risk genetic profile to develop neovascular AMD [4] The phenotypic appearance of Category 3 AMD determines the use of AREDS supplement therapy to decrease the incidence of progression to neovascular AMD [5]. Since the use of AREDS supplements in Categories 1 and 2 AMD has not yet been shown to reduce progression to neovascular AMD [5]. Genetic screening was not presumed to be of benefit to detect whether to use AREDS supplements at an earlier stage than Category 3 AMD Genetic testing of Category 4 AMD patients for the development of more severe atrophic changes was not presumed to be of benefit Genetic testing was not presumed to be of benefit if one eye was already affected by neovascular AMD or advanced atrophic AMD Patients underwent genetic screening at age 65, since only 5.6 % of neovascular AMD develops in patients under the age of 65 years [18] Baseline time: First presentation for neovascular AMD occurs at a mean age of 75 years, as per a combination of multiple clinical trials dealing with therapy for neovascular AMD [18-20, 23, 24, 50, 51] The outcomes included the QALY (quality-adjusted life-year) gain, percent patient value (quality-of-life) gain, and the CUR (cost-utility ratio), or dollars expended per QALY gained ($/QALY) [22] All eyes with neovascular AMD were presumed treated with ranibizumab, including cases presenting with bilateral disease Time tradeoff utilities were derived from a database of over 1100 ophthalmic patients with respective levels of vision loss [22][23][24][30][31][32][33][34][35][36][37][38] Cost perspectives: societal and 3rd party insurer The societal cost perspective included those saved by the better mean vision outcome associated with early-treatment ranibizumab therapy versus late-treatment ranibizumab therapy. They include: (1) direct ophthalmic medical costs = AMD genetic testing costs + incremental annual ophthalmic examination and annual optical coherence tomography costs, (2) direct non-ophthalmic medical costs saved = decreased depression costs, decreased trauma costs, decreased Skilled Nursing Facility costs, decreased nursing costs and other, as yet unidentified, medical costs [40]. (3) direct non-medical costs (caregiver) saved [41] and (4) indirect medical (employment) costs saved [3,42] The 3rd party insurer cost perspective includes: (1) direct ophthalmic medical costs expended and (2) direct non-ophthalmic medical costs saved Cost basis: 2012, average, national, Medicare Fee Schedul Net present value (NPV) analysis discounted patient value outcomes and costs at a 3 % annual rate. All costs were converted to 2012 US real dollars [22] A combined-eye model, a weighted average of first-eye and second-eye models, was utilized to calculate QALY gain per early-treatment case over late-treatment case [23,24] Taking into account the annual conversion rate, the QALY gain and financial value gain accrual rate of 1st eyes with NVAMD was 85.3 % that of 2nd eyes Second eyes in the per patient, early treatment benefit from ranibizumab were assumed to have the same visual outcome as treated first eyes It was assumed that the majority of patients converted to neovascular in one eye first and thus treated with ranibizumab initially in this first eye, though a small number of cases might have present with bilateral neovascular AMD. This assumption is conservative and biases against the analysis by decreasing the overall patient and financial gains AMD age-related macular degeneration, NVAMD neovascular age related macular degeneration, QALY quality-adjusted life-year, CUR cost-utility ratio, MARINA Minimally classic/occult trial of the Anti-VEGF antibody Ranibizumab In the treatment of Neovascular Age-Related Macular Degeneration, SNP single nucleotide polymorphism US in 2012 [2,3]. Central geographic atrophy (AREDS Category 4) in at least one eye was present in 1.24 million, and 8.34 million had drusen ≥125 µm (AREDS Category 3). The 944,000 people aged 65 years with Category 3 drusen (≥125 µm) annually were those who were theoretically screened in our cost-utility model [2,3].
Fifteen-year, incidence data from the Beaver Dam Study [26] suggest approximately 171,350 new cases of NVAMD develop annually in the US. Among these, 5.6 % in the Minimally classic/occult trial of the Anti-VEGF antibody Ranibizumab In the treatment of Neovascular AMD (MARINA) Study [18,20] presented before age 65. We excluded that percentage from our analysis since our model assumed genetic testing at age 65, leaving 161,754 annual new cases.
Ophthalmic utilities are valid [32], reliable [33], and negligibly affected by systemic comorbidities [34]. The Wills Eye Institute Institutional Review Board approved utility acquisition.
Originated at the Center for Value-Based Medicine ® and based upon primary, ophthalmic patient data, the first-eye model assumes vision loss occurs in one eye, while the fellow eye has good vision [22][23][24]36]. In this instance, full patient value gain is not accrued until the fellow eye also develops NVAMD. Utility data from Center for Value-Based Medicine files demonstrate a mean utility difference of 0.0398 between unilateral good vision and 20/40-20/80 vision in the second eye, versus unilateral good vision and ≤20/160 vision in the second eye. This utility gain was weighted to appropriate first-eye model instances herein.
The second-eye model assumes first-eye vision has been lost and the second eye is affected [22][23][24]36]. Thus, greater patient value gain occurs with ranibizumab therapy. The combined-eye model used here integrates weighted first-eye model and second-eye models [22,24]. Extrapolation of data from Barbazetto and colleagues [39] with Markov modeling (TreeAgePro for Healthcare 2012, Williamstown, MA, USA) showed 82 % of patients with unilateral NVAMD in the MARINA/ANCHOR trials developed bilateral NVAMD within 5 years, rising to 96 % by 12 years, the model timeline (Table 3).

Patient value gain
Shah and DelPriore [25] modeled the natural course of untreated NVAMD using control cohorts from six randomized, NVAMD trials. In a meta-analysis using Lineweaver-Burke plots, they demonstrated mean vision loss to 20/640 over 8-9 years, after which vision stabilized. Increasing time since NVAMD highly correlated with increasing vision loss.
Shah and DelPriore data [25] were employed to model MARINA 25-144 month, non-randomized sham results since many sham-treatment patients were allocated to ranibizumab therapy after month 24. Treatment cohort data for months 25-144 were modeled in a LOCF (last observation carried forward) fashion. Twelve years was selected as the model length since this was the average life expectancy of the average NVAMD patient.
An analysis of baseline vision in 50 consecutive Pennsylvania/New Jersey/Delaware patients presenting with first-eye NVAMD in the vitreoretinal practice of author GCB since 2010 was undertaken. The mean, baseline, first-eye vision was 20/182, while that in the fellow eye was 20/47. Overall, 78 % (39/50) presented with vision ≤20/200 in the first eye. Only 18 % (9/50) had first-eye vision ≥20/80 vision at presentation (Table 4).

Costs
The mean, incremental, 12-year, direct, ophthalmic medical costs included genetic testing/monitoring. Ranibizumab therapy costs were excluded since they were assumed similar for early-treatment and late-treatment cohorts, though differences were analyzed in the sensitivity analysis.
Based upon work by Yu et al. [4], genetic testing costs are shown in Table 5. Compounded from $1461 at the time of genetic testing (age 65) to base-case age 75 at the initiation of ranibizumab therapy, they totaled $1906. A $299 cost for an extra, annual, ophthalmic examination and optical coherence tomogram (three/year rather than two/year) was included in the genetic costs for the 22.5 % [4] of genetic-screened high-risk patients progressing to NVAMD. The total cost for genetic testing/monitoring of Stage 3 AMD patients was $2205 per capita.
The base-case scenario shows that 30.3 Category 3 AMD patients required screening/monitoring to facilitate one early-treatment. The total cost of screening/ monitoring for each early-treatment patient was therefore $66,873 (30.3 × $2205).
Javitt and colleagues [39] demonstrated increased direct, non-ophthalmic, medical costs for depression, trauma, Skilled Nursing Facilities, nursing homes and unidentified entities associated with vision loss (Table 6).

Table 3 Fellow eye conversion to neovascular AMD in the MARINA/ANCHOR trials, Barbazetto et al. [39]
Baseline, year 1 and year 2 prevalences are based upon primary data [39], while years 3-12 are based upon the average incidence of conversion to neovascular during years 1 and 2, using a last observation carried forward (LOCF) methodology with Markov modeling AMD age-related macular degeneration   (Table 6). Schmier and associates [40] reported increasing caregiver costs associated with decreasing levels of vision. Early-treatment ranibizumab therapy resulted in a 12-year, (−$172,443) caregiver cost saving vs. late-treatment therapy (Table 6).

Costs
Direct ophthalmic medical costs for early-treatment vs. late-treatment ranibizumab therapy were assumed the same, thus excluded in the base case analysis, but addressed in the sensitivity analysis.
Assuming one early-treatment case per 30.3 genetically screened cases, the base-case genetic testing/monitoring cost for each early-treatment case was $66,873 ( Table 6).
The incremental negative cost for each early-treatment ranibizumab patient was (−$227,455) ( Table 6). With genetic testing/monitoring costs for Category 3 patients screened of $66,873 for each incremental early-treatment case, the overall societal cost per early-treatment case was (−$160,582) ( Table 6).
The national, direct ophthalmic cost for genetic testing/monitoring for an annual cohort of 944,400 Category 3 AMD patients million was $2.082 billion. Total negative costs were $7.083 billion. This resulted in a 12-year, financial return-on-investment (ROI) of 240 % referent to genetic testing/monitoring costs. An incremental $260 million societal saving occurred for each 1 % of patients undergoing early-treatment ranibizumab therapy. When genetic testing facilitated an incremental 12,965 (8.0 %) of the 161,754, annual NVAMD patients in the US to undergo early-treatment ranibizumab therapy, an overall, net financial gain for society accrues    at the rate of $160,582 per additional early-treatment patient.
The financial ROI distribution, assuming that genetic testing for 30.3 Category 3 AMD cases resulted in one incremental early-treatment case is shown in Table 8. The negative cost for each patient screened (cost of $2205) was (−$7500), an overall societal cost of (−$5295), also a 240 %, 12-year societal ROI. The ROI offset Medicare screening costs by 35 %, Medicaid costs by 63 % and commercial insurer costs by 22-24 %. Patients had the greatest ROI for out-of-pocket genetic testing costs, a net $6725. This converted to a 12-year 16,945 % ROI.

Cost-utility ratio (CUR)
$144,000/QALY For a $144,000/QALY CUR, the upper limit of cost-effectiveness in the US according to World Health Organization criteria [43], an incremental 4.1 % of annual NVAMD patients were required to undergo genetic testing-enabled, earlytreatment, ranibizumab therapy. This 4.1 % converts to 6634 patients among the 161,754 annual cohort of new NVAMD patients, 92,200 of whom are not identified as high risk to develop NVAMD by phenotypic features alone (Table 9) [1- 3,9]. It also equates to 1 per 142 of the 944,000 Category 3 AMD patients screened at age 65 annually. For a 3rd party insurer CUR of $144,000/QALY, an increment of 10.1 % of all annual NVAMD patients had to undergo early-treatment for cost-effectiveness (Table 10).
For a $100,000/QALY CUR, the upper limit of costeffectiveness commonly utilized in the US [22], an incremental 4.5 % of annual NVAMD patients were required to undergo early-treatment, ranibizumab therapy for cost-effectiveness (Table 9). For a 3rd party insurer CUR of $100,000/QALY, an incremental 13.2 % of all annual NVAMD patients had to undergo early-treatment for cost-effectiveness (Table 10).

Sensitivity analysis
Sensitivity analysis (Table 11) showed decreasing age made genetic testing considerably less cost-effective (age 40 societal CUR = $1,088,253/QALY) and 3rd party insurer CUR = $231,137/QALY). Deleting extra ophthalmic monitoring costs had negligible effect, while decreasing genetic testing price improved cost-effectiveness. If the cost of ranibizumab therapy for early-treatment cases is twice that of the ranibizumab cost for late-treatment cases, an increment of approximately 6.0 % (9700) of NVAMD cases undergoing early-treatment ranibizumab therapy is required for genetic testing to be cost-effective using WHO criteria.
While the US has no formal, cost-effectiveness upper limits, interventions costing ≤$100,000/QALY are generally believed cost-effective [22]. Formal World Health Organization standards indicate interventions costing ≤3× GDP per capita (~US $144,000) per DALY (disability-adjusted life-year), a metric similar to the QALY, are cost-effective (Tables 9, 10) [42]. Screening is still costeffective if only 4.1 % overall NVAMD cases, or 7.2 % of cases not forecast phenotypically, receive genetic testingfacilitated early-treatment ranibizumab therapy The presence of AMD, even with good vision, can decrease a patient's quality-of-life [31]. We believe low-risk/ medium-risk genetic profiles for progression to advanced AMD, likely allay patient fears and improve patient qualityof-life. We are uncertain how a positive, high-risk genetic profile affects patient quality-of-life, but since only 22.5 % of screened patients have a high-risk profile [4], the overall quality-of-life gain in the low-risk and medium-risk genetic profile cohorts could possibly outweigh total quality-of-life loss in the high-risk profile cohort.

Wealth of the nation
The data herein support the work of Nordhaus [43], the Yale economist who estimated 50 % of the wealth of the United States created during the twentieth century occurred from healthcare advances. While secondary to patient value gain, the increase in national wealth associated with medical interventions is an important factor. If 12,965 (8.0 %) of the 62,279 NVAMD cohort patients not predicted phenotypically to develop NVAMD are recruited to early-treatment due to genetic testing, the cost of testing is at a breakeven point. Each patient undergoing early-treatment in addition adds $160,582 to societal wealth.

When to genetically screen
We selected the age of 65 years as the most cost-effective age for genetic screening since it encompasses 94.4 % of those who develop NVAMD [18]. As sensitivity analysis shows, the earlier genetic testing is performed, the greater the expense of testing, since analyses must account for the time value of money.

Table 8 12-year return-on-investment (ROI) for early-treatment (per patient screened) for ranibizumab therapy for neovascular AMD
Note the direct ophthalmic medical costs associated with ranibizumab therapy are the same for the early-treatment and late-treatment ranibizumab therapy cohorts, thus not integrated. Costs with parentheses () indicate negative costs that accrue against the direct ophthalmic medical costs expended for ranibizumab therapy AMD age-related macular degeneration    Patients with NVAMD may not come in promptly due to numerous reasons, including: (1) unawareness of NVAMD symptoms [44], (2) not realizing vision is decreased in one eye, (3) denial, (4) absence of pain, (5) believing refraction or cataract is their problem, (6) cognitive difficulties and (7) others. In non-ophthalmic specialties, well-defined follow-up plans [45], good relationships with healthcare providers [46], and focused programs [46] result in greater patient adherence. While we cannot be certain, we are hopeful that high-risk phenotypic/genotypic profile patients will be especially aware to present promptly when they develop NVAMD symptoms.

12-year costs (US 2012 real dollars
To our knowledge, convincing data that show more frequent ophthalmic screening allows earlier NVAMD treatment are lacking. Nonetheless, we included the extra costs of screening herein to be conservative in our economic analysis. Some might argue genetic testing of Category 3 AMD cases is of no benefit over phenotypic progression parameters. While the case for Category 4 atrophic AMD centrally or unilateral NVAMD, phenotypic progression parameters for Category 3 AMD are less reliable [6,47]. Furthermore, only a small increment (4.1 %) in genetic testing-enabled, early-treatment, ranibizumab therapy cases is necessary for screening cost-effectiveness. As genetic testing likely increases in accuracy and decreases in price, the patient and financial value gains will be more pronounced. Though the study was performed in US dollars, WHO criteria are very similar for many developed countries globally [48].

Conclusions
In summary, genetic screening for NVAMD is costeffective by the WHO standard of $144,000/QALY if it facilitates early-treatment with ranibizumab for an incremental 4.1 % of annual NVAMD cases. If genetic testing allows earlier ranibizumab therapy for an incremental one NVAMD case per 142 Category 3 AMD patients screened, it remains cost-effective by WHO standards. Using the often accepted US upper limit of cost-effectiveness of $100,000/QALY, genetic testing for NVAMD is cost-effective if it facilitates an incremental 4.5 % of annual NVAMD cases to undergo early-treatment ranibizumab therapy. This information can be used by clinicians to decide whether genetic testing for neovascular age-related macular degeneration is appropriate for their patients.
Authors' contributions GB, MB, HL, PL and KB participated in the conceptualization of the study, the design of the study, and performance of the analyses. GB and MMB wrote the manuscript with help from HL, PL and KB. All authors read and approved the final manuscript.