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Biomedical subjects

G K Shah

Publications and source records attributed to G K Shah.

At least 19 recordsLinked to original sources
PubMed2003

Ocular photodynamic therapy with verteporfin for choroidal neovascularization secondary to ocular histoplasmosis syndrome.

PURPOSE: To evaluate the use of ocular photodynamic therapy (OPT) with verteporfin in patients with choroidal neovascularization (CNV) from ocular histoplasmosis syndrome (OHS) and to compare these results with those for a natural history group. METHODS: A retrospective chart review was performed to identify cases of CNV secondary to OHS treated with OPT. Complete data were available for 38 of 41 eligible eyes. Data regarding the following variables were abstracted from the patient charts: demographic characteristics, previous surgery, angiographic features, number and timing of treatments with OPT, follow-up time, and visual acuity. The visual acuity results of eyes receiving photodynamic therapy were compared with those for a natural history cohort. RESULTS: On average, OHS patients who received treatment developed 0.88 line of visual improvement. Visual acuity improved or stayed the same in 69% (22 of 32) of eyes, improved by > or = 2 lines in 44% (14 of 32), and improved by > or = 4 lines in 22% (7 of 32). Patients who received OPT were 2.07 times more likely to have improved or constant vision than were those in the natural history group as described in one retrospective series (odds ratio = 2.07; 95% confidence interval, 0.78-5.56; P = 0.162). Thirty-eight percent (12 of 32) of eyes had undergone submacular surgery for CNV before any OPT. CONCLUSIONS: Ocular photodynamic therapy with verteporfin may be beneficial in patients with CNV secondary to OHS, even in the setting of previous submacular surgery.

Adolescent↗
PubMed2002

Validity of the time trade-off and standard gamble methods of utility assessment in retinal patients.

AIM: To assess the validity of the time trade-off (TTO) and standard reference gamble (SRG) techniques of utility assessment in patients with retinal disease. A cross section of eligible patients was studied and validity was determined through their relation with two logical constructs, visual acuity and scores from the Visual Function 14 (VF-14) index. METHODS: The study consisted of eligible patients presenting to a tertiary retinal facility who completed an interview. All patients had best corrected vision of 20/40 or worse in at least one eye. TTO and SRG utilities, as well as a VF-14 questionnaire, were administered through a standardised interview. Demographic and clinical (including Snellen visual acuity) information was also collected. RESULTS: 323 patients met these study criteria. Significant predictors of TTO utilities in the multivariate analysis were vision in the better seeing eye (p<0.01) and VF-14 scores (p<0.01). Significant predictors of standard gamble utilities were also vision in the better seeing eye (p<0.01) and VF-14 scores (p<0.05). CONCLUSION: Both the standard gamble and TTO methods demonstrate strong validity when evaluated against visual acuity in the better seeing eye and the VF-14 score.

Adolescent↗
PubMed2001

Improvement in quality of life from photodynamic therapy: a Canadian perspective.

BACKGROUND: The Treatment of Age-Related Macular Degeneration with Photodynamic Therapy (TAP) Study showed that at 1 year, photodynamic therapy significantly reduced the chances of severe visual loss (15 letters or greater) compared with placebo treatment in patients with "predominantly classic" subfoveal choroidal neovascularization (CNV). We performed a study to determine the expected gain in quality of life associated with photodynamic therapy for the treatment of subfoveal CNV in a Canadian cohort of patients with age-related macular degeneration. METHODS: We created a decision analysis model to determine the incremental gain in quality-adjusted life years (QALYs) associated with photodynamic therapy over placebo over a 2-year period. The analysis was conducted using efficacy data derived from the TAP Study and patient-based utilities collected by means of the time trade-off technique. We conducted one-way and two-way sensitivity analyses to determine the robustness of our model. A Monte Carlo simulation was used to determine whether the observed gain in QALYs with photodynamic therapy was significant. RESULTS: Photodynamic therapy was associated with a relative increase in QALYs of 11.3% compared with placebo. In one-way and two-way sensitivity analyses, the relative increase in quality of life associated with photodynamic therapy ranged from 4.2% to 25.7%. The Monte Carlo simulation showed that the gain in QALYs conferred from photodynamic therapy was statistically significant (p < 0.001). INTERPRETATION: Photodynamic therapy improves the quality of life of Canadians with predominantly classic subfoveal CNV secondary to age-related macular degeneration.

Canada↗
PubMed2001

The cost-effectiveness of photodynamic therapy for fellow eyes with subfoveal choroidal neovascularization secondary to age-related macular degeneration.

PURPOSE: Photodynamic therapy (PDT) has recently been demonstrated to be beneficial for the treatment of subfoveal choroidal neovascularization secondary to age-related macular degeneration (AMD). Herein, we determine the cost-effectiveness of PDT for the treatment of subfoveal choroidal neovascularization (CNV) in patients with disciform degeneration in one eye and whose second and better-seeing eye develops visual loss secondary to predominantly classic subfoveal CNV. The analysis was performed from the perspective of a for-profit third-party insurer. DESIGN: Cost-utility Markov models were created to determine the cost-effectiveness of PDT under two different scenarios, by using efficacy data derived from the Treatment of Age-Related Macular Degeneration with Photodynamic Therapy (TAP) Study and patient-based utilities. METHODS: Decision analyses were performed by incorporating data from the TAP Study, expected longevity data, and patient-based utilities. Cost-effective models were then created by incorporating incremental medical costs. Various sensitivity analyses were carried out to determine the robustness of our models. A Monte Carlo simulation was also used to determine whether there was a significant difference in quality-of-life adjusted years (QALYs) gained between PDT therapy and the placebo. RESULTS: For the hypothetical patient whose second and better-seeing eye becomes affected and who has 20/40 vision at baseline in this affected eye (base case 1), PDT was associated with a 10.7% relative increase in their quality-of-life (treatment conferred an additional undiscounted 0.1342 QALYs over a 2-year period). For the hypothetical patient whose second and better-seeing eye becomes affected and who has 20/200 vision at baseline in this affected eye (base case 2), PDT was associated with a 7.8% relative increase in their quality-of-life (treatment conferred an additional undiscounted 0.0669 QALYs over a 2-year period). Sensitivity analysis showed our models were robust and that PDT was usually the dominant treatment choice. Our cost-effective model demonstrated that the cost for a QALY was $86,721 (US dollars discounted at 3%) for base case 1, assuming 5.5 treatments; and $173,984 (USD discounted at 3%) for base case 2. CONCLUSIONS: PDT will cost a third-party insurer $86,721 for an AMD patient with 20/40 vision in the better-seeing eye to obtain one QALY and $173,984 for an AMD patient with 20/200 vision in the better-seeing eye to obtain one QALY. PDT can be considered to be a treatment that is of only minimal cost-effectiveness for AMD patients who have subfoveal CNV in their second and better-seeing eyes and who have good presenting visual acuity at baseline. It is a cost-ineffective treatment for AMD patients who have poor visual acuities in their affected better-seeing eyes.

Aged↗
PubMed2001

The cost-effectiveness of early vitrectomy for the treatment of vitreous hemorrhage in diabetic retinopathy.

Diabetic vitrectomy has been found to be efficacious for the treatment of vitreous hemorrhage secondary to diabetic retinopathy. The purpose of this study is to determine the cost-effectiveness of early vitrectomy for the management of vitreous hemorrhage secondary to diabetic retinopathy. The analysis was performed from the perspective of a third-party insurer. A cost-utility Markov model was used to determine the cost per quality-adjusted life year (QALY) gained from early versus deferral of vitrectomy. The model used 2-, 3-, and 4-year results from the Diabetic Retinopathy Vitrectomy Study, patient-based utilities, life expectancy data, and incremental medical costs. Early vitrectomy was the dominant strategy and was associated with a gain of 0.41 QALYs over the 57-year expected life span for a hypothetical patient. The cost per additional QALY gained from early vitrectomy treatment was $1910 (US$ discounted at 3%). When sensitivity analyses were performed by varying efficacy probabilities and utilities across their 95% confidence intervals, early treatment was always the dominant strategy. Additionally, even at the extreme sensitivity values, the cost per QALY of early vitrectomy treatment remained under $10,000. Overall, early vitrectomy for the treatment of vitreous hemorrhage secondary to diabetic retinopathy is highly cost-effective.

Adult↗
PubMed2000

Arteriovenous adventitial sheathotomy for the treatment of macular edema associated with branch retinal vein occlusion.

PURPOSE: To report arteriovenous adventitial sheathotomy for treatment of macular edema associated with branch retinal vein occlusion. METHODS: Case reports with review. Five eyes of five patients with best-corrected visual acuity of less than 20/200 secondary to branch retinal vein occlusion had pars plana vitrectomy and arteriovenous adventitial sheathotomy and were followed postoperatively for a mean of 6.5 years (range, 5 to 7 years). RESULTS: In four of five eyes, the best-corrected visual acuity improved to 20/30 to 20/70. In the remaining eye, visual acuity remained at finger counting secondary to macular ischemia. CONCLUSION: Arteriovenous adventitial sheathotomy may be beneficial for select patients with poor vision secondary to branch retinal vein occlusion.

Aged↗
PubMed2000

Intralenticular Candida species abscess in a premature infant.

PURPOSE: To report the clinical and histopathologic findings of a premature infant with severe retinopathy of prematurity complicated by the development of an intralenticular fungal abscess. METHODS: Case report and literature review. RESULTS: A markedly premature infant developed Candida septicemia at 29 weeks postconception. Over the ensuing 10 weeks, cataract and intraocular inflammation developed sequentially in each eye, as did progressive retinopathy of prematurity with tractional retinal detachment. Pars plana vitrectomy and lensectomy revealed intralenticular Candida species abscess. CONCLUSION: Progressive cataract and intraocular inflammation in a low birth weight infant may be caused by endogenous intraocular infection secondary to systemic candidiasis. Cataract secondary to retinopathy of prematurity is rare.

Abscess↗
PubMed2000

Converting visual acuity to utilities.

BACKGROUND: Utility theory can be used to quantify dysfunction associated with various diseases and thus can represent a "hard" measure of quality of life. By determining utility values, one can compare the quality of life of patients with ocular disease to that of patients with non-ophthalmic problems. We performed a study to determine whether utility values from patients with ocular disease are associated with clinical variables, including visual acuity in the better-seeing eye, and to develop a mathematical method for converting visual acuity to utility value, if there is an association between the two. METHODS: Cross-sectional study. A total of 239 patients from a tertiary care retinal practice with various ocular conditions, including macular degeneration, cataract, glaucoma and diabetic retinopathy, were interviewed under standardized conditions to determine their utility values by the time trade-off technique. Visual acuity, duration of visual loss and number of concomitant conditions were also determined. Multiple linear regression was performed to determine which variables were associated with utility values. RESULTS: The mean acuity in the better-seeing eye was 0.479 (near 20/40 vision). The mean utility value was 0.72. Accordingly, the average patient in our series was willing to trade 2.8 of every 10 remaining years of life to obtain perfect vision in both eyes. Utility value was significantly associated with visual acuity in the better-seeing eye (F = 69.1, p < 0.001). Other variables were not significantly associated with utility value. The association with duration of visual loss approached statistical significance (p = 0.075). Utility values (U) for patients with ocular disease can be derived from the following formula: U = (0.374)(visual acuity in better-seeing eye) + 0.514. INTERPRETATION: Utility values from patients with ocular disease were strongly associated with visual acuity and could be estimated mathematically.

Aged↗
PubMed2000

Characteristics of patients presenting with central retinal artery occlusion with and without giant cell arteritis.

BACKGROUND: In patients with concurrent central retinal artery occlusion (CRAO) and giant cell arteritis (GCA), prompt recognition and early treatment are crucial to prevent further visual loss in the contralateral eye. The objective of this study was to describe a series of patients with CRAO resulting from GCA and to compare them with patients with isolated CRAO. METHODS: The patient database for a retina service in Philadelphia was searched to identify patients admitted between 1983 and 1993 with a diagnosis of biopsyproven GCA and CRAO. For every patient with CRAO caused by GCA, the next patient admitted for management of acute isolated CRAO was identified; these latter patients constituted the control group. The visual acuity and baseline characteristics of the two groups were compared. RESULTS: Eleven patients with acute CRAO and GCA were admitted during the study period. In both the case and control groups seven patients (64%) were women and nine patients (82%) were white. Six subjects (54%) in the case group and seven (64%) in the control group had a history of hypertension; the values for diabetes mellitus were two (18%) and zero respectively. Four patients (36%) with CRAO and GCA were cigarette smokers, compared with eight patients (73%) with CRAO alone. None of these differences were statistically significant. Patients with CRAO related to GCA were more likely than those with isolated CRAO to have counting fingers or better vision at presentation (odds ratio 2.22 [95% confidence interval 0.37 to 13.2]), but this trend was not statistically significant. INTERPRETATION: Patients who presented with CRAO related to GCA were more than twice as likely as those with CRAO alone to have counting fingers or better visual acuity at the time of presentation. However, owing to the small sample, the power of this study to detect a true difference between the two groups was limited.

Adult↗
PubMed2000

Visual outcomes following the use of intravitreal steroids in the treatment of postoperative endophthalmitis.

OBJECTIVE: To compare visual outcomes between cases of acute postoperative endophthalmitis that did or did not receive intravitreal steroids. DESIGN: Retrospective nonrandomized comparative trial. PARTICIPANTS: Fifty-seven patients with postoperative endophthalmitis. INTERVENTION: Thirty-one patients with postoperative endophthalmitis resulting from cataract extraction received both intravitreal antibiotics and steroids, whereas the remaining 26 received only intravitreal antibiotics. MAIN OUTCOME MEASURES: Improvement in visual acuity. RESULTS: Multivariate logistic regression was used to analyze the variables that potentially influence a three-line visual acuity improvement. The mean baseline visual acuities of both groups were comparable. The use of intravitreal steroids reduced the probability of developing a three-line improvement in visual acuity (odds ratio [OR] = 0.287; 95% confidence interval [CI] [0.072-0.852]). On the basis of logistic regression analysis using our multivariate model, gender, baseline visual acuity, and pars plana vitrectomy were not significantly associated with visual outcome differences between the two groups. CONCLUSIONS: Patients who received intravitreal steroids had a significantly reduced likelihood of obtaining a three-line improvement in visual acuity. At a minimum our study provides no support for their use and, therefore, steroids may not be efficacious for acute endophthalmitis related to cataract extraction.

Acute Disease↗
PubMed2000

The cost-effectiveness of grid laser photocoagulation for the treatment of diabetic macular edema: results of a patient-based cost-utility analysis.

Grid laser therapy has been demonstrated to be of benefit for the treatment of diabetic macular edema. The purpose of the present study was to determine the cost-effectiveness of grid laser therapy for the treatment of diabetic macular edema. The analysis was performed from the perspective of a third-party insurer. Decision analyses and cost-effectiveness analyses were performed by incorporating the data from the Early Treatment Diabetic Retinopathy Study, expected longevity data, and patient-based utilities. Various sensitivity analyses were performed to determine the robustness of the models. Laser treatment conferred an overall improvement in quality-of-life adjusted years of approximately 3 months over the duration of disease for a hypothetical patient. The unadjusted cost per quality-of-life adjusted year (QALY) was US$3,101. Net present value analysis demonstrated that the cost per QALY could increase to $3,655, assuming a 5% discount rate. Overall, grid laser photocoagulation for diabetic macular edema is a very cost-effective treatment based on the results of this cost-utility analysis.

Adult↗