Urate-lowering therapy, serum urate, inflammatory biomarkers, and renal function in patients with gout following pegloticase discontinuation

BACKGROUND/PURPOSE

Little is known about long-term clinical outcomes or urate-lowering (ULT) therapy use following pegloticase discontinuation. We examined ULT use, serum urate (SU), inflammatory biomarkers, and renal function following pegloticase discontinuation.

METHODS

We conducted a retrospective analysis of gout patients who discontinued pegloticase using the Rheumatology Informatics System for Effectiveness (RISE) registry from 1/2016 to 6/2022. We defined discontinuation as a gap ≥ 12 weeks after last infusion. We examined outcomes beginning two weeks after last dose and identified ULT therapy following pegloticase discontinuation. We evaluated changes in lab values (SU, eGFR, CRP and ESR), comparing on- treatment (≤ 15 days of the second pegloticase dose) to post-treatment.

RESULTS

Of the 375 gout patients discontinuing pegloticase, median (IQR) laboratory changes following discontinuation were: SU: +2.4 mg/dL (0.0,6.3); eGFR: -1.9 mL/min (- 8.7,3.7); CRP: -0.8 mg/L (-12.8,0.0); and ESR: -4.0 mm/hr (-13.0,0.0). Therapy post-discontinuation included oral ULTs (86.0%), restarting pegloticase (4.5%), and no documentation of ULT (9.5%), excluding patients with multiple same-day prescriptions (n = 17). Oral ULTs following pegloticase were: 62.7% allopurinol, 34.1% febuxostat. The median (IQR) time to starting/restarting ULT was 92.0 days (55.0,173.0). Following ULT prescribing (≥ 30 days), only 51.0% of patients had SU < 6 mg/dL. Patients restarting pegloticase achieved a median SU of 0.9 mg/dL (IQR:0.2,9.7) and 58.3% had an SU < 6 mg/dL.

CONCLUSION

Pegloticase treats uncontrolled gout in patients with failed response to xanthine oxidase inhibitors, but among patients who discontinue, optimal treatment is unclear. Based on this analysis, only half of those starting another ULT achieved target SU. Close follow-up is needed to optimize outcomes after pegloticase discontinuation.

Intensive urate-lowering with pegloticase plus methotrexate co-therapy in uncontrolled gout patients with and without chronic kidney disease: A retrospective case series

Chronic kidney disease (CKD) and gout commonly co-occur. Pegloticase lowers serum urate (SU) in uncontrolled gout patients but antidrug antibodies limit urate-lowering response and increase infusion reaction (IR) risk. Methotrexate (MTX) co-administration increases pegloticase response rate and mitigates IR risk but CKD limits MTX use. This pooled case series examined pegloticase + MTX co-therapy in uncontrolled gout patients with and without CKD. Cases of pegloticase + MTX co-therapy in existing datasets were retrospectively examined. Baseline eGFR classified patients as CKD (eGFR < 60 mL/min/1.73 m2) or non-CKD (eGFR ≥ 60 mL/min/1.73 m2). Patient characteristics, treatment parameters, laboratory values, urate-lowering response rate (≥12 pegloticase infusions received and SU < 6 mg/dL just before infusion 12), and AEs were examined. Fifteen CKD (eGFR: 43.2 ± 11.3 mL/min/1.73 m2; SU: 8.6 ± 2.2 mg/dL), 27 non-CKD (eGFR: 82.9 ± 19.0 mL/min/1.73 m2; SU: 9.5 ± 1.7 mg/dL) patients were included. Comorbidity profiles were similar, but CKD patients were older (72.0 ± 9.9 vs 52.3 ± 14.3 years) and more often female (33.3% vs 7.4%). Treatment parameters were similar with 4-week MTX Run-in followed by mean of 14.7 ± 8.1 [CKD] vs 14.1 ± 7.1 [non-CKD] pegloticase infusions. However, CKD patients had lower MTX dose (14.8 ± 5.8 vs 19.3 ± 4.9 mg/week). Urate-lowering response was similar (92% vs 86%). eGFR increased during treatment in 60% of CKD (+11.5 ± 20.9 mL/min/1.73 m2, 87% stable/improved CKD-stage) and 44% of non-CKD (+4.2 ± 15.0 mL/min/1.73 m2) patients. AEs were similar (≥1 AE CKD: 53%, non-CKD: 67%; gout flare most-reported). One case each of pancytopenia and IR (mild) occurred in non-CKD patients. These real-world data show similar pegloticase + MTX efficacy in CKD and non-CKD patients. No new safety signals were identified, with most CKD patients showing renal function stability or improvement during therapy.

Monosodium urate crystal depletion and bone erosion remodeling during pegloticase treatment in patients with uncontrolled gout: Exploratory dual-energy computed tomography findings from MIRROR RCT

OBJECTIVE

Monosodium-urate (MSU) crystal deposits can be visualized and quantified with dual-energy CT (DECT). Pegloticase lowers serum urate (SU) in uncontrolled gout patients, with methotrexate (MTX) co-therapy recommended to increase SU-lowering response rate and decrease infusion reaction risk. The literature on serial DECT-imaging during pegloticase+MTX co-therapy is sparse, with only 2 prior cases of rapid MSU deposition depletion with subsequent bone-erosion remodeling reported from a small open-label trial. Here, we report DECT findings during pegloticase treatment in a larger number of patients from a randomized controlled trial to confirm bone-erosion remodeling that follows MSU depletion with pegloticase. The influence of length-of-therapy is also explored.

METHODS

Patients received pegloticase (8mg every 2weeks)+MTX (15mg/week orally) or pegloticase+placebo (PBO) during the MIRROR RCT trial. A subset underwent DECT-imaging on Day1 (first pegloticase infusion) and at Weeks 14, 24, and 52. Patients with paired baseline-Week 52 images were included. Imaged regions with baseline MSU-crystal volume (VMSU)<0.5cm3 were excluded to minimize artifact contributions. VMSU and bone-erosion remodeling were assessed.

RESULTS

Eight patients (6 MTX, 2 PBO) were included. Included patients had received 52weeks (5 MTX), 42weeks (1 PBO), and 6weeks (1 MTX, 1 PBO) of pegloticase therapy. Patients who prematurely discontinued pegloticase maintained SU<6mg/dL on allopurinol (n=2)/febuxostat (n=1). At Week 52, VMSU had markedly decreased in both the pegloticase+MTX and pegloticase+PBO treatment groups, with faster depletion during pegloticase therapy. Bone-erosion remodeling was observed in 29/42 (69%) evaluated erosions: 29 (69%) size decrease, 4 (9.5%) recortication, 3 (7.1%) new bone formation.

CONCLUSION

Rapid VMSU depletion during pegloticase therapy was observed with concomitant bone remodeling within 1year. Following pegloticase discontinuation, VMSU reduction slowed or stopped even when SU was maintained<6mg/dL with oral ULT.

CLINICAL TRIAL REGISTRATION

NCT03994731.

Comparison Between Early-Onset and Common Gout: A Systematic Literature Review

INTRODUCTION

Gout is an inflammatory, metabolic disease associated with a high comorbidity burden including cardiovascular disease, hypertension, type 2 diabetes, hyperlipidemia, renal disease, and metabolic syndrome. Approximately 9.2 million Americans have gout, making prognosis and treatment outcome predictors highly important. About 600,000 Americans have early-onset gout (EOG), generally defined as first gout attack at ≤ 40 years of age. However, data on EOG clinical features, comorbidity profile, and treatment response are sparse; this systematic literature review provides insight.

METHODS

PubMed and American College of Rheumatology (ACR)/European Alliance of the Associations for Rheumatology (EULAR) abstract archives were searched for early-onset gout, "early onset gout," and ("gout" AND "age of onset"). Duplicate, foreign language, single case report, older (before 2016), and irrelevant/data insufficient publications were excluded. The age of diagnosis categorized patients as having common gout (CG, generally > 40 years) or EOG (generally ≤ 40 years). Applicable publications were extensively reviewed/discussed among authors for inclusion/exclusion consensus.

RESULTS

A total of 283 publications were identified, with 46 (35 articles, 10 abstracts) reviewed and 17 (12 articles, 5 abstracts) ultimately included. Eleven reported clinical characteristics, with 6 EOG-CG retrospective/cross-sectional comparisons. Gout diagnosis preceded cardiometabolic comorbidity and renal comorbidities were less prevalent in EOG than CG patients. EOG patients had more severe disease (more gout flares, polyarticular disease), higher pre-therapy serum urate (SU), and worse oral urate-lowering therapy response. Genetics-focused publications reported higher incidences of dysfunctional urate transporter mutations in EOG patients.

CONCLUSIONS

This review suggests that EOG is more recalcitrant to urate-lowering therapy, is associated with urate transporter defects, and carries heavy disease burden. Therefore, early rheumatology referral and urate-lowering in a treat-to-target fashion may benefit EOG patients. Interestingly, EOG patients had fewer cardiometabolic comorbidities at diagnosis than CG patients, presenting a potential "window of opportunity" to attenuate cardiometabolic comorbidity development with SU control. Preventing gout-related suffering and health burden is particularly important in these young EOG patients who will live with gout and its sequelae for decades.

Community Practice Experiences with a Variety of Immunomodulatory Agents Co-Administered with Pegloticase for the Treatment of Uncontrolled Gout

Objective

Patients with uncontrolled/refractory gout have heavy disease burden, but few treatment options. Pegloticase lowers serum urate (SU), but anti-drug antibodies can limit treatment efficacy. Evidence supports immunomodulator-pegloticase co-administration to increase sustained urate-lowering rates, but published cases are limited. This study investigated experience with pegloticase-immunomodulation co-therapy at two community rheumatology practices.

Methods

Patients initiating pegloticase with immunomodulation in 2017 or later were included. Patient/treatment characteristics and proportion of responders (≥ 12 pegloticase infusions, SU < 6 mg/dl at infusion-12) were examined. Patients on therapy at data collection with < 12 infusions were excluded from response analyses. eGFR before and after therapy was examined.

Results

Thirty-four patients (79% male, 62.4 ± 16.3 years) with uncontrolled gout (SU = 9.1 ± 2.0 mg/dl, 91% tophaceous) were included. Most-reported comorbidities were hypertension (76%), obesity (71%), osteoarthritis (68%), and CKD (47%). Pre-therapy eGFR was 65.4 ± 25.2 ml/min/1.73 m² (41% eGFR < 60 ml/min/1.73 m²). All patients initiated immunomodulation before (5.3 ± 3.0 weeks, n = 32) or at (n = 2) first pegloticase infusion. Subcutaneous methotrexate (15.4 ± 4.9 mg/week, n = 20), oral methotrexate (15.3 ± 3.6 mg/week, n = 9), mycophenolate mofetil (1000 mg/day, n = 3), and azathioprine (100 mg/day, n = 2) were administered. Patients received 14.6 ± 7.1 infusions over 28.5 ± 14.9 weeks. Overall response rate was 89%, ranging among immunomodulators (subcutaneous methotrexate: 93%, oral methotrexate: 89%, mycophenolate mofetil: 100%, azathioprine: 50%). On average, eGFR increased during therapy (+ 10.3 ± 16.9 ml/min/1.73 m²), with CKD stability/improvement in 85%. Nineteen patients (56%) experienced gout flares. No infusion reactions or infections were noted. No new safety concerns were identified.

Conclusions

These real-world findings provide further support for increased pegloticase response rates when co-treatment with immunomodulating therapy is used.

Patients with gout that does not respond to oral urate-lowering therapies have heavy disease burden and few treatment options. Pegloticase lowers serum urate levels (SU) and resolves tophi, but anti-drug antibodies can limit urate-lowering efficacy duration. Evidence increasingly supports co-administering an immunomodulator with pegloticase to increase the proportion of patients with sustained urate-lowering response. However, there are few published cases from real-world clinical practice. This study examined treatment with pegloticase + immunomodulation at two community rheumatology practices. Patients who began treatment with pegloticase and an immunomodulator in 2017 or later were included. The proportion of patients with sustained urate-lowering response (≥ 12 infusions received, SU < 6 mg/dl at infusion 12) was investigated. Renal function before and after therapy was also examined. Thirty-four patients were included. Before treatment, SU averaged 9.1 mg/dl and most-reported comorbidities were hypertension (76%), obesity (71%), osteoarthritis (68%), and chronic kidney disease (47%). All patients began using an immunomodulator before or at first pegloticase infusion (subcutaneous methotrexate [20 patients], oral methotrexate [9 patients], mycophenolate mofetil [3 patients], and azathioprine [2 patients]). On average, 14.6 infusions were administered over 28.5 weeks and overall response rate was 89%. Response rate varied among different immunomodulators: subcutaneous methotrexate: 93%, oral methotrexate: 89%, mycophenolate mofetil: 100%, azathioprine: 50%. On average, kidney function improved, with chronic kidney disease stage stability/improvement in 85% of patients. Nineteen patients (56%) experienced gout flares. No infusion reactions or infections were noted and no new safety concerns were identified. These real-world findings provide further support for administering immunomodulation as co-therapy to pegloticase.

Inflammatory and non-inflammatory thyroid eye disease: comparison of disease signs, symptoms and quality of life in US patients

OBJECTIVE

Thyroid eye disease (TED) is an autoimmune, inflammatory disease resulting in retro-orbital fat and extraocular muscle expansion. TED quiets ("inactivates") as inflammation wanes, but signs/symptoms often persist. Disease signs/symptoms and quality of life (QOL) impact were examined in non-inflammatory and inflammatory TED.

METHODS

Moderate-to-severe TED patient data were collected from treating physicians. Clinical activity score (CAS, 6/7 measures available) assessed TED as inflammatory (CAS≥3) or non-inflammatory (CAS=0-1). QOL impact was scored as 1="not at all impaired" to 7="extremely impaired." Non-inflammatory TED patients were further grouped into longer (>3 years) and shorter (≤3 years) disease.

RESULTS

Inflammatory (N=307) and non-inflammatory (N=281) patients had comparable age (50.0±13.3, 48.3±13.8 years), sex (66%, 64% female), TED duration (4.0±4.9; 4.6±5.5 years), and proportion smokers (15%, 11%). Most common non-inflammatory TED signs/symptoms included ocular dryness/grittiness (77%), proptosis (56%), excessive tearing (43%), soft tissue edema (42%), conjunctival redness (24%) decreased vision (24%) and eye muscle involvement (22%; 14% had diplopia). All were less reported than in patients with inflammatory TED. QOL was impacted by non-inflammatory TED, but to a lesser degree than inflammatory disease (3.6±1.5 vs. 4.7±1.4). However, mental health issues were similarly reported. Non-inflammatory TED patients with longer disease (9.0±6.0 years) had similar QOL impact, mental health diagnoses, and TED sign/symptoms as those with shorter disease (1.4±1.0 years).

CONCLUSION

TED signs/symptoms often chronically persist long after TED has "quieted," continuing to impact patient QOL and mental health. These data suggest that moderate-to-severe TED should be thought of as a robust symptomatic chronic disease, regardless of inflammatory status.

POS1164 COMPARISON OF PATIENTS WITH EARLY-ONSET GOUT AND COMMON GOUT: A CLAIMS-BASED ANALYSIS

Background

Data from the United States indicate that 8% of gout patients have disease onset before 40 years of age (early-onset gout [EOG]),1,2 with similar age stratification in the United Kingdom, The Netherlands, and New Zealand.3 At diagnosis, EOG patients have lower rates of renal and cardiometabolic comorbidities than their counterparts who developed gout at a later age.4-6 Published reports also indicate that patients with EOG are less responsive to urate-lowering therapy4 and more often have severe gout, with higher flare rate4-6 and polyarticular disease occurrence.4,5 At present, the literature is limited in comparisons between EOG and common gout (CG) patients.

Objectives

These claims-based analyses on a very large population examined and compared characteristics and comorbidity profile of patients with EOG and CG.

Methods

Patients with ≥1 ICD-9 or -10 gout code were identified in the Symphony claims database using Bellweather software (PearlDiver Technologies™). All patients were in the database ≥2 years before and ≥3 years after first gout code. Patients were said to have EOG if their first gout code occurred before 40 years of age. Patient demographics and comorbidities were compared to those with CG, defined here as first gout code at ≥50 years of age.

Results

68,709 and 933,375 patients were classified as having EOG (mean age: 33.2±5.0 years) and CG (66.3±8.3 years), respectively. The EOG group had a higher proportion of men (72% vs. 62%). EOG and CG patients were in plan for a mean of 5.74±1.57 and 5.72±1.61 years, respectively after first gout diagnosis code. Prior to first gout code, comorbidity rates were lower in EOG than CG patients, including hypertension, cardiovascular disease, diabetes, stroke/transient ischemic attack, and renal disease. Additionally, the proportion of EOG and CG patients with hypertension, type 2 diabetes, and chronic kidney disease codes increased following the first gout code at a faster rate than in the general US population of a similar age (Figure 1).7-9 As a result comorbidity rates were markedly higher in both EOG and CG groups in the years following gout diagnosis.

Conclusion

In agreement with prior studies,4-6 these claims-based analyses suggest that patients with EOG have a lower comorbidity burden than patients with CG, though still higher than the general US population. Importantly, our data suggest that, in the years following gout diagnosis, EOG patients develop comorbidities at a faster rate than their peers without gout. Further study of how gout influences comorbidity development in EOG patients is warranted to better understand and verify these claims-based findings.

References

[1]Zhu Y, et al. Arthritis Rheumatol 2011;63:3136-41.

[2]Chen-Xu M, et al. Arthritis Rheumatol 2019;71:991-9.

[3]Kuo CF, et al. Nat Rev Rheumatol 2015;11:649-62.

[4]Pascart T, et al. Arthritis Care Res 2019;71:986-92.

[5]Zhang B, et al. Medicine 2016;95:e5425.

[6]Li Y et al. ACR Open Rheumatol 2019;1:397-402.

[7]Fryar C, et al. NCHS Data Brief 2017:1-8.

[8]Mendola et al. NCHS Data Brief 2018:1-8.

[9]Coresh, et al. Am J Kidney Dis 2003;41:1-12.

Disclosure of Interests

Anthony Amatucci Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Lissa Padnick-Silver Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Brian LaMoreaux Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, David Bulbin Speakers bureau: Abbvie, Alexion, Sanofi, Consultant of: Norvartis, Abbvie, Alexion

AB1048 ESTIMATED GLOMERULAR FILTRATION RATE CHANGES IN UNCONTROLLED GOUT PATIENTS CO-TREATED WITH PEGLOTICASE AND METHOTREXATE: A RETROSPECTIVE CASE SERIES

Background

Gout patients are at increased risk for developing chronic kidney disease (CKD)1 and hyperuricemia is an independent risk factor for CKD worsening,2,3 particularly in women.3 As a result, renal function is of concern in uncontrolled gout patients. Pegloticase, a recombinant PEGylated uricase, can rapidly decrease serum uric acid levels (sUA) in uncontrolled gout patients, but with pegloticase monotherapy <50% have sustained urate-lowering during Month 6 of treatment.4 Pegloticase treatment response rate is markedly higher when immunomodulating therapies such as methotrexate (MTX) are co-administered,5,6 but MTX use can be limited by renal impairment. Clinical trials excluded CKD patients, but real-world published cases of immunomodulation-pegloticase co-therapy have included patients with a pre-therapy eGFR <60 ml/min/1.73 m2.

Objectives

This study examined pooled case data from prior studies, focusing on renal function changes during MTX-pegloticase co-treatment in patients with and without pre-therapy CKD.

Methods

This retrospective study examined deidentified case data collected for prior retrospective studies.7-9 All patients who underwent MTX-pegloticase co-therapy were included and categorized as CKD (baseline eGFR <60 ml/min/1.73 m2) or non-CKD (baseline eGFR ≥60 ml/min/1.73 m2). sUA, renal function, blood cell counts, and liver function were closely monitored during therapy. Patient characteristics, pegloticase treatment parameters, proportion of treatment responders (≥12 infusions received and sUA <6 mg/dL at infusion 12 [ongoing patients with <12 infusions excluded]), renal function changes (eGFR, CKD stage), and adverse events were examined.

Results

15 uncontrolled gout patients with CKD (9 stage 3a, 4 stage 3b, 2 stage 4; pre-therapy mean[±SD] eGFR: 43.2±11.3 ml/min/1.73 m2, sUA: 8.5±2.2 mg/dL) and 27 without CKD (pre-therapy eGFR: 82.9±19.0 ml/min/1.73 m2; sUA: 9.5±1.7 mg/dL) were included. Patient characteristics and comorbidity profiles were similar, but CKD patients were older (72.0±9.9 vs. 52.3±14.3 yrs) and more often female (33% vs. 7%). On average, MTX was initiated ~4 wks before pegloticase in both CKD status groups. MTX dose was lower in CKD patients (14.8±5.8 vs. 19.3±4.9 mg/wk). Pegloticase treatment was similar between groups (CKD: 14.7±8.1 infusions over 28.5±17.1 wks, non-CKD: 14.1±7.1 infusions over 27.9±15.1 wks), with similar urate-lowering response rate (92% vs. 86%). eGFR increased during therapy in 60% and 44% of CKD and non-CKD patients, respectively, with mean eGFR increase of 11.5±20.9 and 4.2±15.0 ml/min/1.73m2, respectively. In the CKD group, CKD stage either improved or was stable in 13/15 patients (87%). The 2 patients with CKD progression both moved from stage 3a to 3b, and both stage 4 CKD patients had an eGFR increase, improving to stage 3a. In the non-CKD group, 3 patients developed stage 3 CKD (2 stage 3a, 1 stage 3b). 7/15 (47%) CKD and 13/27 (48%) non-CKD patients had ≥1 AE noted, with gout flare most reported (47% vs. 41%). A mild infusion reaction and pancytopenia occurred in 1 non-CKD patient each.

Conclusion

In this retrospective real-world review of a limited number of cases, MTX-pegloticase co-therapy resulted in sustained sUA lowering in uncontrolled gout patients with and without CKD. Close monitoring of renal function indicated stability or improvement during therapy in 86% of uncontrolled gout patients with CKD. Further study is needed to better understand therapy tolerance and treatment response rates of uncontrolled gout patients with CKD undergoing MTX-pegloticase co-therapy.

References

[1]Roughley MJ et al. Arthritis Res Ther 2015;17:90

[2]Edwards NL. Cleve Clin J Med 2008;75:S13-6

[3]Iseki K et al. Am J Kidney Dis 2004;44:642-50

[4]Sundy et al. JAMA 2011;306:711-20

[5]Botson J et al. J Rheum 2021;48:767-74

[6]Keenan RT et al. Semin Arthritis Rheum 2021;51:347-52

[7]Albert J et al. Rheumatol Ther 2020;7:639-48

[8]Broadwell A et al. Arthritis Rheumatol 2021;73 (suppl 10)

[9]Masri KR et al. Ann Rheum Dis 2020;79:450

Disclosure of Interests

John Albert Speakers bureau: Horizon Therapeutics, Consultant of: Horizon Therapeutics, Aaron Broadwell Speakers bureau: Horizon Therapeutics, Consultant of: Horizon Therapeutics, Karim Masri Shareholder of: Horizon Therapeutics, Speakers bureau: Horizon Therapeutics, Consultant of: Horizon Therapeutics, Lissa Padnick-Silver Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Brian LaMoreaux Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics

AB1041 REAL-WORLD REPORTING OF GOUT FLARES IN UNCONTROLLED GOUT PATIENTS CO-TREATED WITH PEGLOTICASE AND METHOTREXATE

Background

Acute gout flares are a known result of urate-lowering in gout patients1 and are the most common adverse event in patients treated with pegloticase.2 Fortunately, the proportion of pegloticase-treated patients who experience flares and the number of flares/patient decrease over time.3 Though well-studied in the clinical trial setting, little has been published on the rate of acute gout flares during pegloticase therapy in a real-world, rheumatology setting. This retrospective study examined one community practice’s findings on gout flares in uncontrolled gout patients co-treated with pegloticase and methotrexate.

Objectives

This retrospective chart review examined acute gout flare occurrence and characteristics in patients undergoing pegloticase-methotrexate co-therapy. Patients with and without gout flares were also compared to investigate potential factors that may have influenced gout flare.

Methods

All patients who underwent pegloticase plus methotrexate co-therapy between January 2017 and March 2021 at a community rheumatology practice were included. Patient, treatment, and flare characteristics were extracted from the medical record and compiled into a de-identified data set.

Results

29 patients treated with pegloticase and methotrexate (28 subcutaneous, 1 oral) were included. Mean patient age was 59.9±17.0 years and 79% were male. Gout duration was 11.7±10.8 years, pre-therapy serum uric acid (sUA) averaged 9.4±1.8 mg/dL, and 97% had visible tophi. Patients had received 12.8±14.3 pegloticase infusions over 25.1±9.7 weeks, with pre-infusion sUA<6 mg/dL in 27/29 patients (93%) at last pegloticase dosing. 23 gout flares were noted in 12 patients (41%, 1.9±1.8 flares/patient), 59% of which were noted as severe and 50% involved a single joint. Acute gout flare was most common in the first 4 weeks of therapy, with first flare occurring a mean of 3.4±2.1 weeks after first pegloticase infusion. Demographic and treatment characteristics were similar between flaring and non-flaring patients. However, patients with ≥1 flare were older (65.8±15.4 years vs. 55.6±17.8 years), more often obese (83% vs. 47%), and had an overall higher comorbidity burden.

Conclusion

This retrospective study of real-world pegloticase use suggests that gout flare rates may be lower in a real-world setting (41%) than that reported in clinical trials (76─86%2,3), which have different gout flare criteria. Consistent with clinical trials,2,3 flare rate was highest during the first 4 weeks of pegloticase treatment, progressively decreasing over time. Interestingly, these data suggest that patients who experience gout flares on pegloticase may have more obesity and a higher comorbidity burden than those who do not experience flares. Further examination of gout flares during real-world pegloticase use is warranted.

References

[1]Pillinger MH, Mandell BF. Semin Arthritis Rheum 2020;50:S24-30.

[2]Sundy JS, et al. JAMA 2011;306:711-20.

[3]Botson JK, et al. J Rheumatol 2021;48:767-74.

Disclosure of Interests

John Albert Speakers bureau: Horizon Therapeutics, Consultant of: Horizon Therapeutics, Lissa Padnick-Silver Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Brian LaMoreaux Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics

POS1162 PREVALENCE AND IMPACT OF DERMATOLOGIC CONDITIONS IN PATIENTS WITH GOUT

Background

Gout is the most common inflammatory arthritis in adults and affects approximately 3-5% of the population in Europe and the United States.1 Chronic hyperuricemia leads to monosodium urate (MSU) crystal deposition in both joints and soft tissues, including the heart, eyes, kidney, skin, and liver.2 Systemic manifestations of gout have been well-characterized, with dermatologic involvement typically described as subcutaneous tophi, miliary gout, gouty panniculitis, and gout nodulosis.2 Other dermatologic conditions may occur more often in gout patients and provide better understanding of a patient’s overall condition.

Objectives

This claims-based study examined the prevalence of dermatological conditions in a large US population of gout patients. Patients with and without dermatologic conditions (identified by diagnosis codes) were compared to assess comorbidity burden, review healthcare utilization, and better understand the underlying consequences of dermatological manifestations of gout.

Methods

The Symphony 2012-2017 claims database was searched to identify patients with ≥1 ICD-9 or -10 gout code (ICD-9: 274.xx, ICD-10: M1*) using Bellweather software (PearlDiver Technologies™). All patients were in the database ≥1 year before and ≥2 years after first gout code (index). Patients were said to have a dermatologic condition if they had ≥1 diagnosis code for atopic dermatitis (ICD-9: 6918, ICD-10: L2*), psoriasis (ICD-9: 6961, ICD-10:L4*), osteomyelitis (ICD-9:73008, ICD-10: M86*), melanoma (ICD-9:1729, ICD-10: C43*), peripheral ulcers (ICD-9: 70710), varied cutaneous abscesses (ICD-9: 9829, ICD-10: L022*), or cellulitis (ICD-9:6826, ICD-10: L03*). Diagnosis code prevalence and healthcare utilization were examined and compared between those with/without a dermatological diagnosis code.

Results

Of the nearly 1.7 million identified gout patients, 29% had ≥1 dermatology diagnosis code. Patients with and without ≥1 dermatology code were of similar age at index (62.72 vs. 61.84 years) but those with ≥1 code were less often male (62% vs. 65%). The most common dermatological codes identified included cellulitis (10.7%), dermatitis (4.8%), psoriasis (2.2%), and osteomyelitis (2.1%, Table 1). Overall, comorbidity diagnosis codes were more prevalent in patients with ≥1 dermatology code, including hypertension, chronic kidney disease, cardiovascular disease, and type 2 diabetes (Table 1). Additionally, healthcare utilization and pain medication use were higher in gout patients with dermatological conditions despite similar ULT use.

Table 1.

Incidence of select dermatologic conditions in gout vs general US populations and comorbidity prevalence among gout patients with/without ≥1 dermatological diagnosis code.

Dermatologic conditionsGout populationGeneral US populationp-valueCellulitis, incidence, cases/100,000 person-yrs10941993<0.001Osteomyelitis, incidence, cases/100,000 person-yrs219224<0.001Gout pts with ≥1 dermatology code (N=488,356)Gout pts without a dermatology code (N=1,201,082)Age, years, mean ± SD62.72 ± 12.3561.84 ± 12.67----Male, n (%)305,012 (63%)779,103 (65%)<0.001Comorbidity, n (%) Hypertension446,577 (91%)1,040,381 (87%)<0.001 Chronic kidney disease215,670 (44%)408,826 (34%)<0.001 Cardiovascular disease358,930 (73%)749,577 (62%)<0.001 Type 2 diabetes254,914 (52%)435,911 (36%)<0.001

Conclusion

These claims-based analyses suggest the prevalence of dermatologic conditions other than those historically associated with gout. Additionally, gout patients with dermatologic conditions had higher comorbidity burden than those without. Therefore, as with other conditions, the skin may provide clues of a larger, systemic disease burden.

References

[1]Kuo CF, et al. Nat Rev Rheumatol 2015;11:649-62.

[2]Khanna P, et al. J Clin Med 2020;9:3204.

[3]McNamara DR, et al. Mayo Clin Proc 2007;82:817-21.

[4]Momodu II, Savaliya V. Osteomyelitis. In: StatPearls. Treasure Island (FL): StatPearls Publishing; August 11, 2021.

Disclosure of Interests

Julie Shiyayo: None declared, Lissa Padnick-Silver Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Brian LaMoreaux Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics

Enhancing the Response Rate to Recombinant Uricases in Patients with Gout

Refractory, or uncontrolled, gout is a chronic, progressive, inflammatory arthropathy resulting from continued urate deposition after failed attempts to lower serum uric acid below the therapeutic threshold with oral urate-lowering therapies such as allopurinol and febuxostat. Recombinant uricase is increasingly being used to treat refractory gout; however, the immunogenicity of uricase-based therapies has limited the use of these biologic therapies. Antidrug antibodies against biologic therapies, including uricase and PEGylated uricase, can lead to loss of urate-lowering response, increased risk of infusion reactions, and subsequent treatment failure. However, co-therapy with an immunomodulator can attenuate antidrug antibody development, potentially increasing the likelihood of sustained urate lowering, therapy course completion, and successful treatment outcomes. This review summarizes evidence surrounding the use of immunomodulation as co-therapy with recombinant uricases.

Effect of Leflunomide on Pegloticase Response Rate in Patients with Uncontrolled Gout: A Retrospective Study

Background

Pegloticase, a PEGylated uricase for uncontrolled gout, rapidly lowers serum urate (SU). Not all patients complete a full-therapy course because anti-pegloticase antibodies can develop, causing efficacy loss and infusion reactions. The literature and clinical trial data indicate that methotrexate co-administration markedly improves pegloticase response rates from the established monotherapy response rate of 42%. Unfortunately, methotrexate use is restricted by kidney disease, which is often present in uncontrolled gout patients. Leflunomide is less restricted in patients with renal dysfunction. This study examined the treatment response rate of pegloticase co-administered with leflunomide.

Methods

Patients co-treated with pegloticase (8 mg biweekly infusion) and oral leflunomide (20 mg/day) were included. Patient/treatment characteristics and safety parameters (adverse events [AEs], laboratory parameters) were examined. Pre-infusion prophylaxis was administered (day of infusion: IV solumedrol, night before and morning of infusion: oral fexofenadine or diphenhydramine). Patients were considered treatment responders if ≥ 12 pegloticase infusions were administered and pre-infusion SU < 6 mg/dl at infusion-12.

Results

Ten patients (five male, 72.7 ± 12.5 years) were included. The most common comorbidities were chronic kidney disease (90%), hypertension (70%), diabetes mellitus (60%), obesity (60%), and congestive heart failure (50%). Baseline SU was 7.1 ± 2.4 mg/dl and nine patients (90%) had subcutaneous tophi noted. Seven patients (70%) met responder criteria, receiving 26.6 ± 14.0 infusions (range 13–55) with a pre-infusion-12 SU of 0.9 ± 1.5 mg/dl. The three non-responders received < 12 infusions because of unrelated AEs or loss of follow-up. Three patients (30%) experienced AEs. One had unrelated cardiac disease worsening and three gout flares, one had a pre-infusion solumedrol reaction (wooziness/loss of consciousness), and one had two mild, transient increases in liver enzymes.

Conclusions

This study supports leflunomide as co-therapy to pegloticase in uncontrolled gout patients. Heterogeneity and high comorbidity burden in uncontrolled gout patients makes having a variety of immunomodulators options important.

Quality of Life in Patients with Chronic Thyroid Eye Disease in the United States

INTRODUCTION

Thyroid eye disease (TED) is an autoimmune condition producing ocular pain, dysmotility, and ocular structure and function changes. As disease activity changes, redness, swelling, and pain can improve, but eye comfort, appearance, and motility alterations often persist. There are limited data on chronic TED patient-reported outcomes. This study examined chronic US TED patient-reported symptoms and quality of life (QOL).

METHODS

Existing data from an online survey regarding chronic TED signs/symptoms and patient QOL were retrospectively examined. The Graves' Ophthalmopathy QOL instrument (GO-QOL; 0-100, 100 = highest QOL) evaluated overall, appearance, and vision-related QOL. Influencing factors were examined by stratifying patients into low (overall QOL ≤ 50), moderate (> 50 and < 75), and high (≥ 75) QOL categories.

RESULTS

One hundred patients (47 women, 81 Caucasian, 45.2 ± 7.6 years) were included. The duration of inactive TED was 3.0 ± 4.6 years and total duration of TED was 5.8 ± 5.9 years. Patients reported an average of 20 doctor visits/year and high prevalence of anxiety (34%) and depression (28%). Prior TED treatments for the polled population included systemic corticosteroids during active TED (25%), orbital radiation (5%), and surgery (25%). The overall GO-QOL score was 60.5 ± 21.8 (vision-related: 58.6 ± 24.0, appearance-related: 62.3 ± 25.1). Patients with low QOL more frequently reported hypothyroidism, anxiety, and a larger number of chronic TED signs/symptoms (average: 4.2). Compared to high QOL patients, low QOL patients had more pain (39% vs. 13%), blurry vision (30% vs. 17%), and diplopia (27% vs. 3%, all p ≤ 0.025). Additionally, the low QOL group more often had TED-specific surgical history (45% vs. 10%, p = 0.002), more often reported disability/unemployment (21% vs. 3%, p = 0.055), and had a higher number of doctor visits (40 vs. 5 visits/person/year, p < 0.001).

CONCLUSION

TED severely impacts patient QOL, despite becoming stable and chronic. Patients reported vision and appearance impairment and psychosocial impact long after acute TED had subsided.

Characteristics of Diabetic and Nondiabetic Patients With Thyroid Eye Disease in the United States: A Claims-Based Analysis

OBJECTIVE

Thyroid eye disease (TED) is a debilitating autoimmune disease characterized by ocular and periorbital tissue inflammation, proptosis, and visual impairment. The known risk factors for TED include radioactive iodine therapy, female sex, and smoking. The risk factors for severe TED include hyperthyroidism, male sex, smoking, and diabetes; however, little is known about how diabetes mellitus (DM) influences TED. This claims-based analysis examined TED characteristics in patients with and without diabetes.

METHODS

Symphony database (2010-2015 U.S. claims) was mined for patients with ≥1 Graves' disease diagnosis code and ≥1 TED-associated eye code, including proptosis, strabismus, diplopia, lid retraction, exposure keratoconjunctivitis, and optic neuropathy (ON). DM status was determined based on type 1 or type 2 diabetes coding. Sight-threatening TED was defined as ≥1 ON or exposure keratoconjunctivitis code.

RESULTS

A total of 51 220 patients were identified. Of them, 2618 (5.1%) and 12 846 (25.1%) had type 1 and type 2 DM, respectively. Patients with and without DM had similar characteristics, but patients with DM were more often men (type 1: 30.3%, type 2: 28.7% vs no DM: 20.5%; both P < .001) and older at the first TED code. In patients with DM, strabismus (25.4%, 22.6% vs 19.9%) and diplopia (38.6%, 37.9% vs 29.9%) occurred more often but proptosis occurred less often (42.3%, 46.3% vs 58.5%; all P < .001). Sight-threatening TED occurred more often in patients with DM because of higher ON rates.

CONCLUSION

Patients with TED and DM may have more extraocular muscle involvement. Furthermore, the higher prevalence of severe TED stemmed from higher ON rates, possibly associated with diabetes-related vasculopathies. These hypothesis-generating data warrant further exploration.

The effect of immunomodulators on the efficacy and tolerability of pegloticase: a systematic review

INTRODUCTION

Pegloticase is a recombinant PEGylated uricase that converts relatively insoluble urate to highly water-soluble allantoin, which is readily excreted by the kidneys. It is the first and only biologic treatment indicated for refractory or uncontrolled gout. Clinical trials showed a 6-month pegloticase responder rate of 42%, with the non-responder rate largely being attributed to the development of high-titer anti-drug antibodies (ADAs) against pegloticase. Immunomodulation attenuates ADA formation to biologics in a number of autoimmune conditions, but their use with pegloticase for uncontrolled gout is less established. This systematic review examined published cases of refractory gout patients treated with immunomodulation in combination with pegloticase.

METHODS

Published cases of immunomodulation with pegloticase were identified in a PubMed search and in abstract databases of major rheumatology society meetings (2012-2020). Duplicate and review articles were excluded, as were those that did not include cases of pegloticase use with immunomodulation. Cases with off-label pegloticase administration schedules were also excluded. Pegloticase response was defined according to each study's specified standard.

RESULTS

Ten publications describing 82 cases of pegloticase use in the setting of immunomodulation were identified. Overall pegloticase response rate was 82.9%. Patients co-treated with an individual immunomodulator had the following response rates: methotrexate: 87.5% (35 of 40 patients), mycophenolate mofetil: 86.4% (19 of 22 patients vs. pegloticase monotherapy [placebo]: 40% [4 of 10 patients]), azathioprine: 63.6% (7 of 11 patients), and leflunomide: 66.7% (4 of 6 patients). A single patient was co-treated with cyclosporin and was a responder. The two patients treated with more than one immunomodulator were both responders.

CONCLUSION

Published reports suggest that immunomodulation co-therapy has the potential to markedly improve pegloticase responder rates in patients with uncontrolled gout.

Characteristics, Comorbidities, and Potential Consequences of Uncontrolled Gout: An Insurance-Claims Database Study

INTRODUCTION

Gout is a common, progressive, systemic inflammatory arthritis caused by hyperuricemia. Current guidelines recommend that serum uric acid (sUA) levels be maintained below 6.0 mg/dl to minimize acute gout attacks, tophi development, and long-term joint and organ damage. This study examined the influence of uncontrolled gout on post-diagnosis comorbidities and medication use.

METHODS

The Humana Research Database (2007-2016, commercial insurance and Medicare) was searched (PearlDiver tool) for patients who had a gout diagnosis code, claims data for at least 6 months before and after diagnosis, and at least 90 days of continuous urate-lowering therapy within 1 year of diagnosis. Patients with controlled (all sUA measurements < 6.0 mg/dl) and uncontrolled (all sUA measurements ≥ 8.0 mg/dl) gout were further examined and compared to better understand the influence of uncontrolled gout on post-diagnosis comorbidities, medication use, and reasons for seeking medical care.

RESULTS

A total of 5473 and 1358 patients met inclusion and classification criteria for the controlled and uncontrolled groups, respectively. Identified comorbidities in both groups included hypertension, hyperlipidemia, diabetes, cardiovascular disease, and chronic kidney disease (CKD). However, the uncontrolled group was more likely to have diabetes, CKD, and cardiovascular disease (including heart failure and atrial fibrillation). Additionally, CKD tended to be more advanced in the uncontrolled gout population (Stage 4-5: 34.6 vs. 22.2%). Overall opioid use was higher in uncontrolled patients.

CONCLUSIONS

The current study identified differences between controlled and uncontrolled gout patients, including usage of medication, severity of CKD, and prevalence of CKD, diabetes, and heart disease.

Trends in Treatment of Active, Moderate-to-Severe Thyroid Eye Disease in the United States

Introduction

Limited data exist on US referral/management patterns for moderate-to-severe thyroid eye disease (TED), a disabling condition.

Methods

US ophthalmologists and endocrinologists experienced in treating TED provided medical record data of moderate-to-severe TED patients and information on referral/treatment practices. Data on signs/symptoms, medical/surgical treatments, treatment response, and referral history were collected. Moderate and severe cases were stratified to interrogate treatment/practice differences.

Results

A total of 181 physicians provided data on 714 patients (49.4 ± 13.6 years old, 65% women, 14% severe disease). Reporting physicians diagnosed 55% of patients themselves and solely managed 37% of cases, with similar referral/comanagement patterns between moderate and severe cases. Topical therapies included lubricating (79%) and glucocorticoid (39%) eye drops. Systemic therapies included oral glucocorticoids (36%), IV glucocorticoids (15%), and rituximab and/or tocilizumab (12%). Few patients underwent orbital radiation (4%) or surgical intervention (4%). IV glucocorticoids (33% vs. 12%), biologics (26% vs. 10%), orbital radiation (11% vs. 3%), and ocular surgery (12% vs. 3%) were used more often in severe versus moderate cases (all P < 0.001). However, severe disease was less responsive to therapy (very responsive to therapy: 28% vs. 49%, P < 0.001).

Conclusions

Participating physicians were primarily responsible for just over one-half of TED diagnoses, but solely treated <40% of patients. Severe TED was treated more often with surgery and systemic immunologic therapies than moderate disease, but was less likely to respond to treatment. These results reinforce that moderate-to-severe TED is difficult to treat with an unmet medical need in the United States.

SAT-424 Assessing Content Validity of the Graves’ Ophthalmopathy Quality of Life Questionnaire (GO-QOL) in the United States

Introduction: Thyroid eye disease (TED) is an autoimmune condition that negatively impacts patient’s quality of life (QOL). The GO-QOL questionnaire was originally developed in the Netherlands to quantify how TED and treatments affect patient QOL. This questionnaire includes eight questions each on visual functioning and appearance related QOL; the items are answered on a 3-point Likert scale and transformed to a 0 (worst) to 100 (best) scale. Though widely used and validated outside the US, the questionnaire has not been validated in the United States (US). Here we examine the content validity.

Methods: Patients with moderate or severe TED were identified using an existing market research patient database, clinician referrals, patient groups, and social media. Interested participants were screened for eligibility prior to completing the GO-QOL. Subjects were also questioned about TED-related signs, symptoms, and treatments and underwent a cognitive interview following GO-QOL completion.

Results: Thirteen TED patients completed the assessments (mean age = 44.8 ± 11.5 years, range: 26-67); all were female. Mean TED duration was 4.6 ± 5.5 years (range: 0.4-20.7). Twelve patients (92.3%) had Graves’ disease and one had Hashimoto’s thyroiditis. Descriptions of how TED signs and symptoms impacted quality of life were consistent with GO-QOL items, and qualitative interviews indicated that patients found the GO-QOL content relevant and complete. Responses indicated that minor wording changes may be needed to account for US cultural and language conventions and prevent confusion (specifically related to a bicycling question [12/13 reported not regularly riding a bike before TED symptom onset]). Visual functioning impacts most commonly-reported during the interview were difficulty driving a motor vehicle (92% of participants), difficulty with electronic screens (e.g., televisions, smart phones, and computers; 77%), difficulty moving around outdoors (including issues with light sensitivity, uneven surfaces, and depth perception; 69%), and difficulty doing hobbies or pastimes (69%). Emotional/psychological impacts frequently reported by participants were change in appearance (92%), depression and anxiety (including fear and worry; 77%), and frustration and anger (including moodiness; 69%). Negative reactions from others (staring, asking questions), social impacts and isolation, and lack of self-confidence and embarrassment were also reported (each 62%).

Conclusion: This analysis of US patient interviews offered strong support for GO-QOL content validity. Therefore, the GO-QOL is appropriate to quantify TED-related QOL impact in a US population. However, a few slight wording modifications may be needed for future optimal use in the US.Reference: Terwee CB. Br J Ophthalmol 1998;82:773-779

Intraretinal pH in Diabetic Cats

PURPOSE

To examine intraretinal extracellular H+ concentration([H+]o) in diabetic cats.

METHODS

Double-barreled H+-selective microelectrodes were used to measure [H+]o as a function of retinal depth ([H+]o profiles) in four cats with different stages of diabetic retinopathy. Profiles from "normal"and "damaged" areas of the retina were compared to profiles previously obtained from healthy cats.

RESULTS

In the healthy retina, [H+]o is generally highest in the middle of the retina and decreases toward the choroid and the vitreous. In 48 % of the profiles from diabetic animals with visible retinopathy, the inner retinal gradient was reversed so that the vitreous was more acidic than the middle of the retina. The profiles with reversed inner retinal gradients were classified as damaged. On the average, the inner retina tended to be 0.07-0.08 pH units more acidic in diabetic animals than in healthy normoglycemic animals, but of similar acidity to healthy hyperglycemic animals. In areas with damaged inner retinal gradients, net H+ production in the outer retina was also impaired.

CONCLUSIONS

While the number of animals is small, we conclude that the [H+](O) distribution varied from normal to damaged in the same retina. Diabetes seems to lead to an acidification of the inner retina that appears to be at least partly related to hyperglycemia and which may be important in the progression of retinopathy.

Genetic Study of Familial Uveal Melanoma

PURPOSE

To evaluate a kindred with familial uveal and cutaneous melanoma and to identify potential genetic and environmental factors that may predispose individuals to develop uveal melanoma.

DESIGN

Family-based case report with detailed clinical and genetic evaluation.

PARTICIPANTS

Ten siblings in a single nuclear family.

METHODS

Evaluation of a large sibship via family history, complete eye and skin examinations, environmental risk factor questionnaire, and genetic testing, as well as a MEDLINE search of familial uveal melanoma kindreds.

MAIN OUTCOME MEASURES

Cutaneous and ocular nevi, benign and malignant neoplasms of skin and other sites, brief skin cancer risk assessment tool risk classification for cutaneous melanoma, DNA sequencing of p16INK4a and p14ARF genes, and citations on familial uveal melanoma.

RESULTS

The proband and his mother had uveal melanoma, 3 cutaneous melanomas occurred among 2 siblings, and 2 other siblings had basal cell carcinomas. No germline mutations were detected in the melanoma-associated tumor suppressor genes p16INK4a and p14ARF. Seven out of 10 siblings had a history of cutaneous and/or ocular nevi. Of the 3 subjects without nevi, 2 had histories of eye or skin malignancies (1 uveal melanoma, 1 basal cell carcinoma). Three of the 10 siblings had relevant ocular findings (2 choroidal nevi, 1 uveal melanoma). Six were also found to be in the "high-risk" classification for cutaneous malignancies based on scores from a previously validated risk assessment tool. This family, combined with the 91 previously reported familial uveal melanoma kindreds, brings to 92 the total number thus far recorded.

CONCLUSIONS

Our results strengthen the association between uveal melanoma, atypical nevi, and cutaneous melanoma. This relationship supports the recommendation that individuals with a personal or family history of uveal melanoma, particularly in combination with atypical nevi, should be regularly screened for uveal and cutaneous melanoma.

The Electroretinogram Components in Abyssinian Cats with Hereditary Retinal Degeneration

PURPOSE

To examine phototransduction using the a-wave and other aspects of retinal function with the intraretinal b- and c-waves at different stages of an inherited photoreceptor degeneration in Abyssinian cats.

METHODS

Vitreal and intraretinal ERGs were recorded from eight dark-adapted, anesthetized Abyssinian cats. Brief bright flashes were used to elicit vitreal a- and b-waves. Longer, weaker flashes were used to elicit intraretinal b- and c-waves. Stages 1 through 4 of the disease were characterized ophthalmoscopically. Parameters of the Lamb and Pugh a-wave model (a(max), A, and t(eff)) for the Abyssinian cats were compared with those for normal cats. Light microscopy was used to count photoreceptor nuclei.

RESULTS

The maximum a-wave amplitude, a(max), was significantly smaller in stage 1, and continued to decrease (stage 1: 50% of normal, stage 2: 28%, stage 3: 27%; and stage 4: unrecordable). There was a small, but not significant, decrease in the amplification constant A from 0.24 +/- 0.11 s(-2) in normal cats to 0.16 +/- 0.08 s(-2) in Abyssinian cats. The intraretinal b- and c-wave amplitudes decreased most dramatically during the early stage of the disease. Affected animals had fewer photoreceptors than unaffected Abyssinians or control animals. The number of photoreceptors declined most rapidly in the inferior periphery.

CONCLUSIONS

The amplitudes of all ERG components were already reduced significantly by stage 1 and progressively declined. The lack of major changes in a-wave model parameters indicates that the degeneration is probably not due to a mutation in transduction proteins. Losses of photoreceptor function were larger than losses of photoreceptor nuclei.

Retinal oxygenation and oxygen metabolism in Abyssinian cats with a hereditary retinal degeneration

PURPOSE

To investigate the effects of a hereditary retinal degeneration on retinal oxygenation and determine whether it is responsible for the severe attenuation of retinal circulation in hereditary photoreceptor degenerations.

METHODS

Seven adult Abyssinian cats affected by hereditary retinal degeneration were studied. Oxygen microelectrodes were used to collect spatial profiles of retinal oxygenation in anesthetized animals. A one-dimensional model of oxygen diffusion was fitted to the data to quantify photoreceptor oxygen utilization (Qo(2)).

RESULTS

Photoreceptor Qo(2) progressively decreased until it reached zero in the end stage of the disease. Average inner retinal oxygen tension remained within normal limits at all disease stages, despite the observed progressive retinal vessel attenuation. Light affected photoreceptors normally, decreasing Qo(2) by approximately 50% at all stages of the disease.

CONCLUSIONS

Loss of photoreceptor metabolism allows choroidal oxygen to reach the inner retina, attenuating the retinal circulation in this animal model of retinitis pigmentosa (RP) and probably also in human RP. As the degeneration progresses, there is a strong relationship between changes in the a-wave of the ERG and changes in rod oxidative metabolism, indicating that these two functional measures change together.

Visual outcomes after accommodating intraocular lens implantation

PURPOSE

To evaluate and compare the visual outcomes and accommodative amplitude in cataract patients after implantation of the Crystalens intraocular lens (IOL) (Eyeonics) versus standard monofocal IOLs.

SETTING

Ten clinics in a nationwide multicenter study in the United States.

METHODS

A multicenter comparative interventional case series with masked randomized postoperative examination of 224 eyes of 112 patients was performed by a single observer. Patients were divided into 2 groups (56 patients; 112 eyes each) depending on which IOL was implanted (Crystalens or monofocal). Accommodation was measured using 1 objective (dynamic retinoscopy) and 2 subjective methods (defocus and near point of accommodation). Visual acuity measurements were performed under the same conditions with standard visual acuity charts.

RESULTS

Uncorrected monocular near vision was significantly better in the Crystalens group than in the standard monofocal group, with 101 of 112 eyes (90%) and 17 of 112 (15%), respectfully, reading J3 or better postoperatively. All 56 Crystalens patients had a binocular uncorrected near visual acuity of J3 or better compared with 16 of 56 (29%) standard monofocal patients. The mean postoperative monocular (0.85 +/- 0.30 [SD] versus 0.70 +/- 0.19, P<.01) and binocular (1.16 +/- 0.17 versus 1.01 +/- 0.14, P<.01) distance uncorrected visual acuities were also better in the Crystalens group than in the control group. All patients in the study achieved a corrected distance visual acuity of 20/20 or better. Measures of accommodation were significantly higher in Crystalens patients than in the monofocal IOL patients (dynamic retinoscopy 2.42 +/- 0.39 diopters [D] versus 0.91 +/- 0.24 D, P<.01; monocular defocus 1.74 +/- 0.48 D versus 0.75 +/- 0.25 D, P<.01; monocular near point of accommodation 9.5 +/- 3.1 inches versus 34.7 +/- 9.8 inches, P<.01). Perceived accommodation (5.79 D) was significantly greater than the measured accommodation (1.96 to 2.42 D) in Crystalens patients (paired t test, P<.01).

CONCLUSIONS

The Crystalens IOL provided better uncorrected near and distance visual outcomes than standard monofocal IOLs in all analyses performed. Patients perceived a greater accommodation than measured. Understanding why this occurred could lead to valuable advances in accommodating IOL technology.

Effect of hypoxemia and hyperglycemia on pH in the intact cat retina

OBJECTIVE

To examine the effects of acute hypoxemia and hyperglycemia on retinal pH to understand hyperglycemia-induced changes in the normal intact cat retina.

METHODS

Spatial profiles of extracellular hydrogen ion (H+) concentration were obtained from the cat retina, in vivo, using pH-sensitive microelectrodes during normoxia (arterial partial pressure of oxygen [PaO2] = 114.5 +/- 7.9 mm Hg), normoglycemia (plasma glucose concentration, 117 +/- 19 mg/dL), acute hypoxemia (PaO2 = 29.5 +/- 2.2 mm Hg), and acute hyperglycemia (plasma glucose concentration, 303 +/- 67 mg/dL). An H+ diffusion model was fitted to the outer retinal data to quantify photoreceptor H+ production. The inner retinal pH was also examined.

RESULTS

Hypoxemia induced a mean acute panretinal acidification of 0.16 pH units that originated from a 2.55-fold increase in net photoreceptor H+ production. Hyperglycemia induced an acute panretinal acidification of 0.12 pH units; however, photoreceptor H+ production levels remained unchanged. Retinal pH changes followed the course of arterial PaO2 and blood glucose changes.

CONCLUSIONS

The increase in photoreceptor H+ production during hypoxemia confirms the importance of glycolysis in the retina. Hyperglycemia-induced pH changes resulted from either increased inner retinal H+ production or decreased H+ clearance/neutralization. Clinical Relevance The hyperglycemia-induced acidification that originates in the inner retina suggests that retinal acidosis may contribute to the development of diabetic retinal disease.

Effect of acute hyperglycemia on oxygen and oxidative metabolism in the intact cat retina

PURPOSE

The Crabtree effect is the phenomenon of inhibition of respiration by glycolysis, as a result of elevated glucose levels. It is not certain whether the Crabtree effect occurs in the retina, which has a high glycolytic capacity. In the current study, in vivo photoreceptor oxygen consumption was examined during the normo- and hyperglycemic states in the dark-adapted cat retina to determine whether the Crabtree effect occurs in the outer retina.

METHODS

Spatial profiles of oxygen tension were obtained in the cat retina, in vivo, with the use of oxygen microelectrodes during control conditions and acute (5.19 +/- 0.83 hour) episodes of hyperglycemia (blood glucose, >350 mg/dL). The outer retinal portions of the profiles were fitted to a model of oxygen diffusion to quantify photoreceptor oxygen consumption.

RESULTS

Photoreceptor oxygen consumption did not significantly change during hyperglycemia compared with control conditions. Choroidal PO(2) decreased during hyperglycemia by an average of 5.8 +/- 7.4 mm Hg. This led to an increase in the fraction of O(2) used by the photoreceptors that was derived from the inner retina. Choroidal PO(2) did not recover when blood glucose levels were returned to normal. Average inner retinal PO(2) was not affected by the episodes of hyperglycemia.

CONCLUSIONS

The Crabtree effect does not occur to any significant degree in the outer retina, because hyperglycemia did not affect photoreceptor oxygen consumption. Choroidal PO(2) decreased during hyperglycemia, and the oxygen deficit was made up by the retinal circulation.

Quantification of in vivo anaerobic metabolism in the normal cat retina through intraretinal pH measurements

We examined intraretinal [H+] in the intact retina of anesthetized cats using H+-sensitive microelectrodes to obtain spatial profiles of extracellular [H+]. One H+ is produced when an anaerobically generated ATP is utilized. We theorized that H+ production directly reflects anaerobic glucose consumption. From the choroid (pH approximately 7.40), [H+]o steadily increased to a maximum concentration in the proximal portion of the outer nuclear layer (pH approximately 7.20). The shape of the profile was always concave down, indicating that a net production of H+ occurred across the avascular outer retina. A three-layer diffusion model of the outer retina was developed and fitted to the data to quantify photoreceptor H+ extrusion into the extracellular space (Q(OR-H+)). It was determined that the outer segment (OS) layer had negligible H+ extrusion. The data were then refitted to a special three-layer model in which the OS layer Q(H+) was set equal to zero, but in which the inner segments and outer nuclear layer produced H+. The resulting Q(OR-H+) was several orders of magnitude lower than previous measurements of Q(OR-lactate), which were based on choroidal mass balances of lactate. Stoichiometrically, one H+ is produced for each lactate produced, so we concluded that Q(OR-H+) is a measure of net rather than total H+ production. Because retinal acid production is so high, the retina must contain efficient H+ clearance and/or neutralization mechanisms that prevent severe acidosis. The effect of light on retinal extracellular [H+] and Q(OR-H+) was also examined. As expected, light adaptation caused a retinal alkalinization that resulted from a 52% reduction in Q(OR-H+). This is in agreement with previous studies that have shown that both oxidative (e.g. Haugh et al., 1990) and glycolytic metabolism (Wang et al., 1997a,c) in the photoreceptor are decreased by a factor of 2 during light adaptation. Although we could not obtain absolute values for outer retinal glycolysis, changes in Q(OR-H+) appear to directly reflect changes in glycolytic metabolism.

Metabolic dependence of photoreceptors on the choroid in the normal and detached retina

PURPOSE

This article assesses the hypothesis that the high blood flow rate and low O(2) extraction associated with the choroidal circulation are metabolically necessary and explores the implications of the spatial relationship between the choroid and the photoreceptors for metabolism in the normal and detached retina.

METHODS

The O(2) distribution across the retinal layers was previously measured with O(2)-sensitive microelectrodes in cat. Profiles were fitted to a diffusion model to obtain parameters characterizing photoreceptor O(2) demand. This was a study of simulations based on those parameters.

RESULTS

Photoreceptor inner segments have a high O(2) demand (QO(2)), and they are far (20 to 30 microm) from the choroid. These unusual conditions require a large O(2) flux to the inner segments, which in turn requires high choroidal oxygen tension (PO(2)), high choroidal venous saturation (ScvO(2)), low choroidal O(2) oxygen extraction per unit volume of blood, and a choroidal blood flow (ChBF) of at least 500 ml/100 g-min. Movement of the inner segments further from the choroid, which occurs in a retinal detachment, severely reduces the ability of the inner segments to obtain O(2), even for detachment heights as small as 100 microm. Depending on detachment height and assumptions about choroidal and inner retinal PO(2) during elevation of inspired O(2) (hyperoxia), hyperoxia is predicted to partially or fully restore photoreceptor QO(2) during a detachment.

CONCLUSIONS

The choroid is not overperfused, but requires a high flow rate to satisfy the normal metabolic demand of the retina. Because the oxygenation of the photoreceptors is barely adequate under normal conditions, detachment has serious metabolic consequences. Hyperoxia is predicted to have clinical benefit during detachment.