Progression of coronary artery disease predicts clinical coronary events. Long-term follow-up from the Cholesterol Lowering Atherosclerosis Study

BACKGROUND

Progression of coronary artery disease is assumed to be a surrogate end point for clinical coronary events. Because no single method or measure for a coronary angiographic end point is uniformly accepted as optimal, the utility and validity of surrogate end points for predicting clinical coronary events remain unsettled.

METHODS AND RESULTS

The Cholesterol Lowering Atherosclerosis Study randomized 162 nonsmoking, 40- to 59-year-old men with previous coronary artery bypass graft surgery to colestipol/niacin plus diet or placebo plus diet. Atherosclerosis change on 2-year coronary angiograms was evaluated by a consensus panel and by quantitative coronary angiography (average per-subject change in percent diameter stenosis [%S] and minimum lumen diameter [MLD). With all three end points, the benefit of colestipol/niacin treatment on coronary artery atherosclerosis has been reported. Annual follow-up for an average of 7 years (range, 6.3 months to 10 years) has been carried out on all subjects who completed the 2-year angiogram. Clinical coronary events (need for revascularization, nonfatal acute myocardial infarction, and coronary death) have been documented. Risk of clinical coronary events was positively related to coronary lesion progression for all three surrogate end points (P<.05). New lesion formation in bypass grafts (P=.02) and progression of mild/moderate lesions ( < 50%S) were predictive of clinical coronary events (P<.01). Change in MLD contributed significantly to the prediction of clinical coronary events beyond a model with %S alone (P<.05).

CONCLUSIONS

In this population of nonsmoking men with previous bypass surgery, both the consensus panel- and quantitative coronary angiography-based end points of coronary artery disease progression predict clinical coronary events. Subjects who demonstrate greater coronary artery lesion progression have an increased risk of future clinical coronary events. Design of shorter, smaller trials of antiatherosclerotic agents is justified.

Baseline characteristics, natural history, and risk factors to progression in eyes with stage 2 macular holes. Results from a prospective randomized clinical trial. Vitrectomy for Macular Hole Study Group

PURPOSE

The purpose of this study is (1) to determine baseline characteristics and natural history of immature full-thickness macular holes, (2) to describe progression and resolution, and (3) to present new aspects of pathogenesis of idiopathic macular hole.

METHODS

The authors analyzed 41 eyes with stage 2 macular holes (37 patients) in a multicentered prospective randomized trial; 19 eyes were randomized to observation (versus surgery) and had more than 12 months of follow-up, allowing determination of the natural course. Baseline and subsequent examinations included best-refracted visual acuity (Early Treatment of Diabetic Retinopathy Study, potential acuity meter, Pelli-Robson contrast sensitivity, and Bailey-Lovie reading vision), of clinical examinations, photography, and fluorescein angiography.

RESULT

Mean Snellen visual acuity was 20/66 at baseline. Centric holes usually had a small break (201 microns average mean diameter) with a dark yellow ring and without significant retinal elevation. Eccentric holes had a high maximum/minimum diameter ratio (mean, 1.88 +/- 0.7) and an incomplete cuff of subretinal fluid or yellow ring. Posterior vitreous detachment prevalence was 32% (8/25) in the centric hole group and 0% (0/ 16) in the eccentric hole group (P < 0.05). For the 19 eyes with 12 months of followup, progression rate to stage 3 (or 4) was 74% (n = 14). The diameter of the stage 2 holes increased significantly between baseline and 12 months (P < 0.001). Progression rate to stage 3 was 100% (8/8) in the eyes with pericentral hyperfluorescence (PCH) and 55% (6/11) in eyes without PCH (P < 0.05). Enlargement occurred in 100% of eccentric holes and 60% of centric holes (P = 0.09). Different progression patterns in eccentric and centric holes suggest different mechanisms of pathogenesis.

CONCLUSION

Eccentric and centric stage 2 macular holes may have a different pathogenesis. Most stage 2 macular holes, especially with PCH (P < 0.05) or eccentric holes, progressed to stage 3 or 4. In addition to purely tangential traction, some component of obliquely oriented anteroposterior vitreous traction component may be important for pathogenesis of senile macular holes, particularly eccentric stage 2 macular holes.

Macular pucker after successful surgery for proliferative vitreoretinopathy. Silicone Study Report 8

BACKGROUND

The prevalence of postoperative macular pucker and the factors associated with its development after successful surgery for proliferative vitreoretinopathy (PVR) using silicone oil or gas tamponade are unknown.

METHODS

The postoperative status of the macula was determined by reviewing the photographs of 336 eyes taken 6 months after randomization. Two hundred eleven eyes with attached maculas were identified and analyzed to determine the prevalence of macular pucker after silicone oil and gas tamponades in eyes without (group 1) and with (group 2) previous vitrectomy surgery. Data obtained at baseline, from the primary study surgery, and from subsequent examinations and repeat surgeries during a follow-up period of 6 months were analyzed for factors associated with postoperative macular pucker.

RESULTS

The 6-month-point prevalence rate of postoperative macular pucker was 15% (32 of 211 eyes). Ten of the 32 eyes were new cases of macular pucker. The authors were unable to document a difference in the 6-month-point prevalence of postoperative macular pucker between group 1 and group 2 eyes (13% versus 18%) or between eyes randomized to gas versus silicone oil (19% versus 12%). Postoperative pucker was three times as likely to develop in aphakic/pseudophakic eyes compared with phakic eyes (P = 0.02). Focal contraction posteriorly causing starfolds, and intravitreal contraction involving the vitreous base or vitreous cavity, were significantly less prevalent in eyes with postoperative macular pucker (P < 0.05). Large (> or = 2 disc diameters) retinal breaks (P = 0.04) were associated significantly with postoperative macular pucker (P = 0.04). The authors were unable to document an association between postoperative macular pucker and the type of adhesive modality used or the extent of its application. Postoperative visual acuity was significantly better if the macula was not puckered (P < 0.01).

CONCLUSIONS

The occurrence of macular pucker after successful surgery for retinal detachments complicated by severe PVR is not influenced by the choice of intraocular tamponade. Certain preoperative factors may be associated with postoperative macular pucker.

Silicone oil in repair of retinal detachments caused by necrotizing retinitis in HIV infection

OBJECTIVE

To evaluate the safety and efficacy of 1000- and 5000-centistoke silicone oil as retinal tamponades for the treatment of retinal detachments secondary to necrotizing retinitis in patients with human immunodeficiency virus (HIV) infection.

DESIGN

A prospective observational study.

SETTING

Community and university-based ophthalmology clinics.

PATIENTS

Three hundred fifty patients with HIV infection, who had 407 eyes with retinal detachments secondary to necrotizing retinitis.

INTERVENTION

Vitrectomy surgery for retinal detachment with 1000- or 5000-centistoke silicone oil as the retinal tamponade.

OUTCOME MEASURES

Efficacy was measured both by anatomic success (defined as complete retinal attachment or macular attachment) and by visual acuity success (defined as preservation of visual acuity or ambulatory vision). Safety was determined by the rate of complications, including abnormal intraocular pressure and corneal and lens opacification.

RESULTS

At the last follow-up examination, the retina was completely attached in 287 (73%) of 393 eyes, the macula was attached in 370 eyes (94%), 268 eyes (68%) had ambulatory vision, and visual acuity was preserved in 219 (56%) of 388 eyes. Corneal opacification, hypotony, and silicone oil emulsification were present in 4%, 2%, and 1% of eyes, respectively. One eye had elevated intraocular pressure. Of the 57 patients who had both eyes treated, 35 died, of whom four (11%) had nonambulatory vision in both eyes. Of the 293 patients who had one eye treated, 122 died, of whom 44 (36%) died with nonambulatory vision in the treated eye. The median time to cataract was 192 days; to nonambulatory vision, 474 days; and to death, 204 days.

CONCLUSIONS

Silicone oil repair of retinal detachments in necrotizing retinitis is an efficacious and safe procedure that delays or prevents loss of vision in advanced HIV disease.

Compensatory vascular changes of remote coronary segments in response to lesion progression as observed by sequential angiography from a controlled clinical trial

BACKGROUND

Local coronary artery enlargement to compensate for atherosclerotic plaques preserves the vessel lumen. The extent to which coronary segments remote from progressing lesions enlarge is unknown. This is clinically relevant since compensatory enlargement may be important in determining whether clinical complications result from progression of coronary artery disease (CAD). Additionally, compensatory change has implications for quantitative coronary angiographic (QCA) trials, since the effect of progression on diameter means may be mitigated by compensatory changes in remote coronary segments when QCA change is averaged over all lesions.

METHODS AND RESULTS

Serial QCA data from 78 subjects in the Monitored Atherosclerosis Regression Study were used to demonstrate compensatory changes in coronary segments remote from progressing or regressing lesions. Coronary segments were first classified as progressing (regressing) if percent diameter stenosis (PS) increased or decreased by > 10 with a concurrent decrease or increase in minimum lumen diameter (MLD) of either > 0.32 mm or > 10% of the normal baseline reference diameter (DNORM). Segments not meeting these criteria were labeled stenosis stable. Stenosis-stable segments opposite progressing lesions showed increases in MLD (P = .0006), DNORM (P = .001), and average diameter (P = .001). On-trial apolipoprotein (apo) B, apo C-III, and blood pressure levels inversely correlated with these compensatory changes.

CONCLUSIONS

Lesion progression in one coronary segment is associated with significant increases in segmental diameter of remote parts of the coronary tree. We hypothesize these increases to be vascular compensatory changes in response to progression of CAD. Vascular compensatory change is enhanced by LDL cholesterol and triglyceride-rich lipoprotein reduction and appears to be part of the treatment effect itself.

Hyperacuity test to evaluate vision through dense cataracts; research preliminary to a clinical study. I. Studies conducted at the University of California at Berkeley before travel to India

BACKGROUND. Patients with dense ocular media disorders retain the ability to project or point to an intense source of light. Using this response capability and high luminance points of light as stimuli, Vernier judgments (a hyperacuity test) can be made by these patients, even without the presence of a "window" through a leucoma, cataract, or bleed. Without coaching, these individuals are able to locate the centers of the individual degraded point images if the individual light sources are adequately separated (i.e., if sufficient "gaps" exist between the individual stimuli), and they can spatially align the degraded images. Advanced cataracts are the main cause of blindness in the developing world, and this is a treatable condition. In these nations, only a modest proportion of affected patients receive surgery, and only 5% or less of these individuals obtain treatment in two eyes. There are incredibly large and rapidly growing backlogs of advanced cataract patients requiring care (many millions). Because of the 20 to 30% failure rates that occur after treatment (all causes) in many developing world settings, a test performed before surgery, which offers a meaningful estimate of postsurgical visual outcome, can be valuable. Using the principle defined above, we seek to determine before surgery those individuals who will derive most benefit from cataract removal, and which of two cataractous eyes has the better postsurgical visual prognosis. EXPERIMENTAL. In Berkeley, we performed a series of preliminary studies on a Vernier acuity test before initiating a clinical study in a developing world setting. These studies were conducted upon young adult normal subjects wearing their usual vision corrections, with and without induced refractive errors, and/or with or without simulated dense nuclear cataracts. We sought (1) to determine the number of repeat trials necessary for reliable outcomes; (2) to compare a two-point and a three-point Vernier acuity display; (3) to determine the shape of the measured response function at large gap separations between test points; (4) to define optimal test distance and stimulus size; (5) to assess the effect(s) of a broad range of uncorrected refractive errors upon outcomes; and (6) to consider means to minimize refraction-based errors by using a pinhole, a refractive correction, and/or selective spatial filtering. We compared responses obtained using the current CRT/VDT-based, computer-driven (Berkeley) instrument with a new precision optical/mechanical computer-driven (India) instrument. The India instrument is needed to determine design parameters for a next stage simpler, cheaper, more rugged field instrument(s).(ABSTRACT TRUNCATED AT 400 WORDS)

Serial coronary angiographic evidence that antioxidant vitamin intake reduces progression of coronary artery atherosclerosis

OBJECTIVE

To explore the association of supplementary and dietary vitamin E and C intake with the progression of coronary artery disease.

DESIGN

A subgroup analysis of the on-trial antioxidant vitamin intake database acquired in the Cholesterol Lowering Atherosclerosis Study, a randomized, placebo-controlled, serial angiographic clinical trial evaluating the risk and benefit of colestipol-niacin on coronary artery disease progression.

SETTING

Community- and university-based cardiac catheterization laboratories.

SUBJECTS

A total of 156 men aged 40 to 59 years with previous coronary artery bypass graft surgery.

INTERVENTION

Supplementary and dietary vitamin E and C intake (nonrandomized) in association with cholesterol-lowering diet and either colestipol-niacin or placebo (randomized).

OUTCOME

Change per subject in the percentage of vessel diameter obstructed because of stenosis (%S) determined by quantitative coronary angiography after 2 years of randomized therapy on all lesions, mild/moderate lesions (< 50%S), and severe lesions (> or = 50%S).

RESULTS

Overall, subjects with supplementary vitamin E intake of 100 IU per day or greater demonstrated less coronary artery lesion progression than did subjects with supplementary vitamin E intake less than 100 IU per day for all lesions (P = .04) and for mild/moderate lesions (P = .01). Within the drug group, benefit of supplementary vitamin E intake was found for all lesions (P = .02) and mild/moderate lesions (P = .01). Within the placebo group, benefit of supplementary vitamin E intake was not found. No benefit was found for use of supplementary vitamin C exclusively or in conjunction with supplementary vitamin E, use of multivitamins, or increased dietary intake of vitamin E or vitamin C.

CONCLUSIONS

These results indicate an association between supplementary vitamin E intake and angiographically demonstrated reduction in coronary artery lesion progression. Verification from carefully designed, randomized, serial arterial imaging end point trials is needed.

The incidence of corneal abnormalities in the Silicone Study. Silicone Study Report 7

OBJECTIVE

To determine factors that were prognostic of corneal abnormalities in eyes following surgery for severe proliferative vitreoretinopathy.

DESIGN

Subgroup analysis of the Silicone Study.

SETTINGS

Community and university-based ophthalmology clinics.

MATERIALS

Eyes with attached maculae at the 24-month follow-up examination that did not have a pre-existing corneal abnormality.

INTERVENTIONS

Vitrectomy surgery with long-acting gas or silicone oil.

OUTCOME MEASURES

Epithelial and/or stromal edema, corneal opacity and/or previous corneal transplant.

RESULTS

The incidence of corneal abnormalities at 24 months was 27% and did not differ significantly between treatment groups. Prognostic factors were preoperative aphakia or pseudophakia (P = .003), preoperative iris neovascularization (P = .006), reoperation (P = .001), the absence of a fluid/gas exchange (P = .03), corneal touch by silicone oil (P = .02), and the presence of aqueous cells (P = .009) or aqueous flare (P = .08). In a multivariate analysis, independent prognostic factors were iris neovascularization (relative risk [RR] = 13.1), aphakia or pseudophakia (RR = 3.0), postoperative aqueous flare (RR = 5.4), and reoperations (RR = 3.4). Corneal abnormalities were correlated with poor visual acuity and hypotony (P < .001).

CONCLUSIONS

To our knowledge, this is the first study to document that the incidence rates of corneal abnormalities are equivalent between oil and gas. The incidence of corneal abnormalities in gas-filled eyes was higher than expected, and remained high in oil-filled eyes, despite the use of an inferior iridectomy. Successful surgical repair of the retinal detachment with a single operation, and prevention and early management of corneal touch by silicone oil should help to prevent corneal abnormalities. If rubeosis iridis or severe aqueous flare is present, preoperative treatment with intense topical and possibly periocular steroids might reduce inflammation, which might mediate corneal damage.

An alternative approach to the optimal design of an LD50 bioassay

In this paper we propose an alternative approach to the optimal design of an LD50 bioassay. We adopt a Bayesian approach to make use of prior information about the location and scale parameters of the tolerance distribution function to select the design parameters (number of doses, total number of animals, centre of doses, space between doses), and we adopt a frequentist approach using the Spearman-Karber statistic to estimate the LD50. We define the optimal design as the one that produces the minimum expected mean squared error E(MSE) with respect to the joint prior distribution of the parameters of the tolerance distribution. For the design parameters investigated, we found: (i) the shape of the E(MSE) is relatively smooth and continuous, the magnitude of which is influenced by the underlying tolerance distribution; (ii) the amount of prior information about the location and scale parameters independently and jointly affect the optimal design; and (iii) as the amount of prior information decreases, one requires more doses and/or animals. Finally, we show the proposed method is robust for an incorrectly assumed tolerance distribution function.

Use of neural networks in predicting the risk of coronary artery disease

Artificial neural networks were created to predict the occurrence of coronary artery disease based on information from the serum lipid profile. The development of the networks involved a strategy which permitted learning from censored observations. The networks were developed with data from the Cholesterol Lowering Atherosclerosis Study, which followed serum lipoprotein levels and clinical events in 162 patients over a period of up to 10 years. Inputs consisted of seven different mean lipid values, and the desired output was the time period during which a complication of coronary artery disease was predicted to occur. Cross-validation was performed by splitting the data into separate training and testing sets, scoring the performance of the neural network strategy on the testing sets, and comparing scores with those obtained from Cox regression models developed on the same training data. Performance of the neural network strategy exceeded that of Cox regression in predicting clinical outcomes (66% vs 56%, McNemar's test P = 0.005). The network design provided an effective approach to predicting outcomes from a clinical trial with variable follow-up times.

Power considerations for testing an interaction in a 2 x k factorial design with a failure time outcome

We examine the power and sample size requirements for testing an interaction in the situation of a 2 x k factorial design with time to failure as the outcome of interest. Using the distribution of a general test statistic, based on weighted residual sum of squares for testing a general interaction in a 2 x k factorial experiment, we describe the relationship between the power of the test and the size of the sample. In a simulation study, we evaluate the behavior of three commonly used estimators as methods for estimating the parameters of the test statistic. These are the Mantel-Haenszel (MH) method, a method (O/E) based on the ratio of the observed to expected number of events, and the maximum likelihood (MLE) method. We show that in most cases nominal test sizes and appropriate powers are attained using the MLE and MH methods, whereas the O/E method yielded test sizes and powers less than expected. With both large baseline hazard rates and large differences in relative hazard rates, the difference between the simulated and asymptotic powers for all three methods become larger; however, the size of this difference is small and unlikely to seriously affect the use of either the MLE or MH methods. The proposed methods could also be used to calculate the power and sample size for testing a treatment-covariate interaction in a stratified data analysis.

Triglyceride- and cholesterol-rich lipoproteins have a differential effect on mild/moderate and severe lesion progression as assessed by quantitative coronary angiography in a controlled trial of lovastatin

BACKGROUND

The Monitored Atherosclerosis Regression Study, a randomized, double-blind, placebo-controlled, 2-year trial of lovastatin monotherapy, found that coronary lesions < 50% diameter stenosis (%S) and coronary lesions > or = 50% S at baseline had different responses to therapy. We now report on clinical, lipid, and nonlipid risk factors of treatment response in these lesion subsets.

METHODS AND RESULTS

Two hundred seventy subjects, 37 to 67 years old, with plasma total cholesterol (TC) 190 to 295 mg/dL (4.91 to 7.63 mmol/L) and total triglyceride < 500 mg/dL (5.65 mmol/L) were randomized to low-fat, low-cholesterol diet and either lovastatin 80 mg/d or placebo. Logistic regression was used to model the association between risk factors and coronary lesion progression in mild/moderate (< 50% S) and severe (> or = 50% S) lesions in 220 angiogram pairs analyzed by computer quantitative coronary angiography. In the placebo group, risk factors (P < .05) for the progression of mild/moderate lesions were triglycerides and TC/high-density lipoprotein cholesterol (HDL-C). Risk factors for the progression of severe lesions were HDL-C (negative), low-density lipoprotein cholesterol (LDL-C)/HDL-C, and TC/HDL-C. TC/HDL-C was the predominant risk factor for both mild/moderate and severe lesions in the multivariate analysis. In the lovastatin group, with aggressive lowering of LDL-C and TC below 85 mg/dL and 156 mg/dL, respectively, risk factors for mild/moderate lesions included triglycerides and very-low-density lipoprotein-LDL-associated apolipoprotein C-III (apo C-III-heparin precipitate), a marker of triglyceride-rich lipoprotein particles. Apo C-III-heparin precipitate was the predominant risk factor in the multivariate analysis. Risk factors for severe lesions were LDL-C, LDL-C/HDL-C, TC/HDL-C, and apo B; LDL-C/HDL-C was the predominant risk factor.

CONCLUSIONS

These results indicate that triglyceride-rich lipoproteins and cholesterol-rich lipoproteins have a differential effect on mild/moderate and severe lesion progression, respectively. These results add to the growing evidence of the importance of triglyceride-rich lipoproteins as a risk factor for coronary artery disease and the need for treatment in the progression of atherosclerosis.

The effects of silicone oil removal. Silicone Study Report 6

OBJECTIVE

To evaluate the advisability of removing silicone oil from eyes after surgery for severe (with a classification of at least C-3) proliferative vitreoretinopathy.

DESIGN

Subgroup analysis of the Silicone Study, a randomized, multicentered, surgical trial.

SETTING

Community- and university-based clinics.

PATIENTS

Two hundred twenty-two eyes with severe proliferative vitreoretinopathy followed up in the Silicone Study.

INTERVENTIONS

Vitrectomy for proliferative vitreoretinopathy with silicone oil as the intraocular tamponade.

OUTCOME MEASURES

Changes in visual acuity, recurrent retinal detachment, and incidence of complications.

RESULTS

Ninety-nine (45%) of 222 eyes had surgery for silicone oil removal (oil-removed eyes). Compared with the eyes that did not undergo silicone oil removal (oil-retained eyes) evaluated at a comparable time after oil injection, oil-removed eyes at the examination prior to oil removal were more likely to be attached (85% vs 40%; P < .0001), have a visual acuity of 5/200 or greater (63% vs 35%; P < .0001), and not be hypotonous (5% vs 22%; P < .001). There was no association between the length of oil retention and incidence of recurrent retinal detachment after oil removal. Eyes with attached retinas at the time of oil removal generally improved in visual acuity at the last follow-up examination (P < .0001), which was not evident in eyes with detached retinas at the time of oil removal. In a matched-pair cohort analysis comparing both sets of eyes, there was an increased risk for recurrent retinal detachment at the last follow-up examination in the oil-removed eyes (odds ratio [OR], 2.1; P = .09). However, overall visual acuity improved for oil-removed eyes in 19 (29%) of 66 pairs and for oil-retained eyes in one (2%) of 66 pairs (OR, 19.0; P < .0001). Although nonsignificant, incidence rates of keratopathy (OR, 0.5) and hypotony (OR, 0.5) were lower in oil-removed eyes.

CONCLUSION

Removal of silicone oil in anatomically successful eyes significantly increases the likelihood of improved visual acuity with a slight increase in the likelihood of recurrent retinal redetachment. There was a trend for a reduction in the incidence of complications in the oil-removed eyes.

Coronary angiographic changes with lovastatin therapy. The Monitored Atherosclerosis Regression Study (MARS)

OBJECTIVE

To assess the effects of lipid-lowering therapy with lovastatin on coronary angiographic findings in patients with coronary artery disease and to compare the findings with those of two lipid-lowering angiographic trials using similar end points.

DESIGN

Randomized, double-blind, placebo-controlled, multicenter coronary angiographic trial.

SETTING

Community- and university-based cardiac catheterization laboratories.

PARTICIPANTS

A total of 270 patients, 37 to 67 years old, with total cholesterol ranging from 4.92 to 7.64 mmol/L (190 to 295 mg/dL) and angiographically defined coronary artery disease.

INTERVENTION

A cholesterol-lowering diet and either lovastatin, 80 mg/day, or placebo.

OUTCOME

Per-patient change in percent diameter stenosis as determined by quantitative coronary angiography (primary end point). Global change score, based on the consensus of blinded expert readers regarding angiographic change (secondary endpoint).

RESULTS

Lovastatin lowered total cholesterol level by 32%, low-density lipoprotein cholesterol by 38%, and the apolipoprotein B by 26% and raised the high-density lipoprotein cholesterol by 8.5% (P < 0.001). Average percent diameter stenosis increased 2.2% in placebo recipients and 1.6% in lovastatin recipients (P > 0.20). For lesions 50% or greater, average percent diameter stenosis increased 0.9% in placebo recipients and decreased 4.1% in lovastatin recipients (P = 0.005). The mean global change score was +0.9 (indicating progression) in the placebo group and +0.4 in the lovastatin group (P = 0.002); 13 placebo recipients and 28 lovastatin recipients had global change scores indicating regression (P < 0.02).

CONCLUSION

Treatment with lovastatin plus diet slows the rate of progression and increases the frequency of regression in coronary artery lesions (by global change score), especially in more severe lesions (by quantitative angiography). This is the third lipid-lowering trial to show a benefit using the global change score, an end point predictive of clinical coronary events. Differences between two of these trials, using quantitative coronary angiographic end points, may have theoretical bearing on the mechanisms by which lipid-lowering therapy operates at the level of the arterial wall.

Relaxing retinotomy with silicone oil or long-acting gas in eyes with severe proliferative vitreoretinopathy. Silicone Study Report 5. The Silicone Study Group

In the Silicone Study, 117 of 404 eyes (29%) with severe proliferative vitreoretinopathy (> or = C-3, full-thickness retinal folds in three or more quadrants) enrolled in the study were treated with vitrectomy, underwent a relaxing retinotomy, and were randomly assigned to treatment with long-acting gas or silicone oil. Forty-six eyes (20%) had undergone no previous vitrectomy (group 1); 71 eyes (42%) had undergone previous vitrectomy (group 2) with intraocular gas tamponade (P < .001). Group 1 eyes not undergoing retinotomy had better anatomic (six months) and visual (six and 24 months) outcomes and less hypotony (six months) than eyes that did regardless of tamponade (P < .05). For eyes undergoing retinotomy, silicone oil decreased the likelihood of hypotony (six months, P < .05). These differences were not found in group 2 eyes. We conclude that eyes undergoing a vitreous operation for the first time for the treatment of proliferative vitreoretinopathy can in most instances be successfully treated by conventional techniques without the need for relaxing retinotomy. Retinotomy may be required more often in patients undergoing repeat vitreous surgery for proliferative vitreoretinopathy, in which case both silicone oil and long-acting perflouropropane gas appear to be equally effective.

Postoperative intraocular pressure abnormalities in the Silicone Study. Silicone Study Report 4

BACKGROUND

Chronically abnormal intraocular pressure (IOP) may follow surgery for proliferative vitreoretinopathy (PVR), using either long-acting gas or silicone oil tamponade. Its prevalence and clinical significance are unclear.

METHODS

In the Silicone Study, 241 eyes with severe (> or = C-3) PVR were treated with vitrectomy, randomized to perfluoropropane gas (C3F8) or silicone oil, and followed for 6 months or longer. Chronic IOP abnormalities, based on findings at two consecutive or any three postoperative visits, were defined as (1) low IOP (hypotony), 5 mmHg or less, or (2) elevated IOP, more than 25 mmHg.

RESULTS

Eleven (5%) eyes had chronically elevated IOP and 58 (24%) had chronic hypotony. Chronically elevated IOP was more prevalent in eyes randomized to silicone oil than in those randomized to C3F8 gas (8% versus 2%; P < 0.05). Chronic hypotony was (1) more prevalent in eyes randomized to C3F8 gas than in those randomized to silicone oil (31% versus 18%; P < 0.05); (2) more prevalent in eyes with anatomic failure (48% versus 16%; P < 0.01); and (3) correlated with poor postoperative vision (P < 0.0001), corneal opacity (P < 0.001), and retinal detachment (P < 0.001). Factors prognostic of chronic hyotony included preoperative hypotony (P < 0.01), diffuse contraction of the retina anterior to the equator (P < 0.01), rubeosis (P = 0.02), and large retinal breaks (P = 0.02). In a multivariate analysis, diffuse contraction of the retina anterior to the equator remained an independent factor prognostic of chronic hypotony (odds ratio = 4.2), regardless of whether the retina was attached postoperatively.

CONCLUSION

Intraocular pressure abnormalities are a common postoperative complication in eyes with PVR, and may occur with either C3F8 gas or with silicone oil. The presence of diffuse contraction of the retina anterior to the equator should alert the vitrectomy surgeon that the eye is likely to be hypotonus postoperatively.

Vitrectomy with silicone oil or perfluoropropane gas in eyes with severe proliferative vitreoretinopathy. Silicone Study Report 3

Between 1985 and 1990, 340 eyes with rhegmatogenous retinal detachment (RRD) and severe (stage C3 or worse) proliferative vitreoretinopathy (PVR) were treated with vitrectomy and randomly selected to receive perfluoropropane gas or silicone oil; 183 eyes had undergone no prior vitrectomy (group 1), and 157 eyes had undergone prior vitrectomy with intraocular gas tamponade (group 2). No differences were found between eyes in the two groups in achieving visual acuity of 5/200 or better (44% vs. 39%), macular reattachment (78% vs. 77%), or complete retinal reattachment (67% for both groups). In group 1, 74 eyes achieved complete retinal reattachment after only one operation; 41 additional eyes achieved reattachment after a second surgical procedure. In group 2, these numbers were 74 and 26, respectively. Eyes treated successfully after more than one operation were less likely to regain a visual acuity of 5/200 or better than those successfully treated with one operation (P < 0.01). There was no difference in hypotony between groups, but keratopathy was more frequent in eyes in group 2 (P < 0.05). The results suggest that differences in outcomes between group 1 and group 2 eyes are not as great as previously believed.

Evaluation of colestipol/niacin therapy with computer-derived coronary end point measures. A comparison of different measures of treatment effect

BACKGROUND

The Cholesterol Lowering Atherosclerosis Study has demonstrated beneficial effect of colestipol/niacin on coronary atherosclerosis using a panel-determined global coronary change score. We now report treatment group comparisons using quantitative coronary angiographic (QCA) measures from all processable segments in 85 of 162 randomly selected baseline/2-year film pairs.

METHODS AND RESULTS

Treatment benefit was established for percent stenosis for either continuous or categorical analyses with regression established regardless of the per-patient scoring procedure. In addition, treatment benefit favoring regression was established in some cases for roughness and for percent involvement, a longitudinal estimate of the percent of coronary surface involved by raised lesions. Benefit on minimum diameter was directly related to whether the segment was proximal to a graft insertion and hemodynamically related to the bypass graft. QCA correlates of panel-determined progression were increases in percent stenosis and numbers of occluded lesions in native arteries and the number of progressing lesions in bypass grafts.

CONCLUSIONS

These results demonstrate that a variety of computer measures can be used as end points in coronary angiographic therapy trials, but change in percent stenosis correlates best with visual panel assessments and best reflects the treatment benefit; when treatment effect sizes are moderate to large, the required sample size of coronary angiographic trials can be reduced when QCA is used.

The Monitored Atherosclerosis Regression Study (MARS). Design, methods and baseline results

OBJECTIVE

The Monitored Atherosclerosis Regression Study (MARS) was designed to evaluate the effect of cholesterol lowering by monotherapy with an HMG-CoA reductase inhibitor on progression/regression of atherosclerosis in subjects with angiographically documented coronary artery disease. The purpose of this paper is to present the design, methods, and baseline results of MARS.

DESIGN

MARS is a prospective, randomized, double-blind, placebo-controlled trial with baseline, 2-year, and 4-year coronary angiography as well as carotid, brachial, and popliteal ultrasonography.

SETTING

Outpatient clinics at the University of Southern California School of Medicine and the University of Wisconsin School of Medicine.

SUBJECTS

Two hundred seventy participants of both sexes were recruited directly from the cardiac catheterization laboratory or by chart review of patients having undergone cardiac catheterization in the past. Subjects were considered eligible if they had angiographically demonstrable atherosclerosis in 2 or more coronary artery segments, unaltered by angioplasty, with at least 1 lesion > or = 50% but < 100% diameter stenosis (%S). The inclusion range for total cholesterol (TC) was between 190 and 295 mg/dL. Exclusion factors were: triglycerides > or = 500 mg/dL; premenopausal females; uncontrolled hypertension; diabetes mellitus; untreated thyroid disease; liver dysfunction; renal insufficiency; congestive heart failure; major arrhythmia; left ventricular conduction defects; or any life-threatening disease.

INTERVENTION

Subjects were placed on a low-fat, low-cholesterol diet and either 40 mg b.i.d. lovastatin (Mevacor) or placebo. Randomization was stratified by sex, smoking status, and TC.

MAIN OUTCOME MEASURES

Per-subject average change in %S as determined by quantitative coronary angiography (QCA) is the primary angiographic endpoint. Secondary endpoints are: categorical analyses of the proportion of subjects with progression; human panel reading of coronary angiograms; and change in minimum lumen diameter (MLD) in mm by QCA. Carotid, brachial, and popliteal ultrasonography is also being performed.

RESULTS

The subjects randomized into MARS are 91.5% male with an age range of 37 to 67 years (mean age 57.9 years). For the cohort, baseline lipids are (mean +/- SD): TC, 231 +/- 24 mg/dL; low-density lipoprotein cholesterol (LDL-C) by ultracentrifugation, 153 +/- 24 mg/dL; LDL-C, by calculation, 157 +/- 23 mg/dL; high-density lipoprotein cholesterol (HDL-C), 43 +/- 10 mg/dL; and triglycerides, 160 +/- 73 mg/dL. There were no significant differences between treatment groups in baseline lipid levels or baseline angiographic characteristics.

CONCLUSIONS

MARS baseline data show adequacy of randomization with comparability of lovastatin and placebo groups in demographic, lipid, and angiographic characteristics.

Low survival rate after cardiopulmonary resuscitation in a county hospital

BACKGROUND

The standard of practice in hospitals in the United States is to perform cardiopulmonary resuscitation on all patients who suffer a cardiac arrest unless a specific order has been written to the contrary. In recent decades, however, data showing a low rate of survival to discharge under certain conditions have accumulated, leading some to question this policy. The objective of this study was to examine variables predictive of patient survival following cardiopulmonary resuscitation using standardized methods of measuring severity of illness.

METHODS

All patients were identified who underwent cardiopulmonary resuscitation on the medicine service at Los Angeles County (California) Hospital from August 15, 1990, to February 15, 1991. Severity of illness was evaluated by examining diagnosis, Acute Physiology and Chronic Health Evaluation II score, and organ system failure. Cases were followed up prospectively until death or hospital discharge, and data concerning post-arrest mental status, utilization of resources, and disposition were gathered.

RESULTS

Of the 131 patients identified, 22 patients (16.8%) survived for 24 hours but died before discharge; only four patients (3.1%) survived to discharge.

CONCLUSIONS

This study suggests that in some settings (eg, institutions that are for sick patients under conditions where monitoring is limited because of scarcity of resources), survival after full cardiopulmonary arrest may be even lower than previously documented.

Comparison of computer- and human-derived coronary angiographic end-point measures for controlled therapy trials

The Cholesterol Lowering Atherosclerosis Study, a randomized angiographic clinical trial, demonstrated the beneficial effect of niacin/colestipol plus diet therapy on coronary atherosclerosis. Outcome was determined by panel-based estimates (viewed in both still and cine modes) of percent stenosis severity and change in native artery and bypass graft lesions. Computer-based quantitative coronary angiography (QCA) was also used to measure lesion and bypass graft stenosis severity and change in individual frames closely matched in orientation, opacification, and cardiac phase. Both methods jointly evaluated 350 nonoccluded lesions. The correlation between QCA and panel estimates of lesion size was 0.70 (p less than 0.0001) and for change in lesion size was 0.28 (p = 0.002). Agreement between the two methods in classifying lesion changes (i.e., regression, unchanged, or progression) occurred for 60% (210 of 350) of the lesions kappa +/- SEM = 0.20 +/- 0.05, p less than 0.001). The panel identified 442 nonoccluded lesions for which QCA stenosis measurements could not be obtained. Lesions not measurable by QCA included those with stenosis greater than 85% that could not be reliably edge tracked, segments with diffuse or ecstatic disease that had no reliable reference diameter, and segments for which matched frames could not be located. Seventy-nine lesions, the majority between 21% and 40% stenosis, were identified and measured by QCA but were not identified by the panel. This comparison study demonstrates the need to consider available angiographic measurement methods in relation to the goals of their use.

A comparison of methods for calculating a stratified kappa

Investigators use the kappa coefficient to measure chance-corrected agreement among observers in the classification of subjects into nominal categories. The marginal probability of classification may depend, however, on one or more confounding variables. We consider assessment of interrater agreement with subjects grouped into strata on the basis of these confounders. We assume overall agreement across strata is constant and consider a stratified index of agreement, or 'stratified kappa', based on weighted summations of the individual kappas. We use three weighting schemes: (1) equal weighting; (2) weighting by the size of the table; and (3) weighting by the inverse of the variance. In a simulation study we compare these methods under differing probability structures and differing sample sizes for the tables. We find weighting by sample size moderately efficient under most conditions. We illustrate the techniques by assessing agreement between surgeons and graders of fundus photographs with respect to retinal characteristics, with stratification by initial severity of the disease.

Methods, statistical features, and baseline results of a standardized, multicentered ophthalmologic surgical trial: the Silicone Study

This article describes the trial design and baseline results for the Silicone Study, a multicenter, randomized surgical trial designed to compare the effectiveness of silicone fluid versus long-acting gas in the treatment of proliferative vitreoretinopathy (PVR). Design features include (1) standardization of the surgical protocol to reduce intersurgeon variability, (2) formulation of a PVR clinical classification system relevant to modern vitreoretinal surgery, and (3) creation of a photographic protocol to document PVR pathology. Statistical issues affecting the analysis of the outcome data include (1) the addition of a second group of patients with more severely diseased eyes after the trial began, (2) the change to a different long-acting gas during the course of the trial, and (3) recurrent retinal detachments that require reoperations with the randomized treatment, and, in some instances, a crossover from the randomized to the alternate treatment. Demographic and baseline ocular characteristics are presented for the two groups under study.

Fat and cholesterol intake of attendees at two national USA cardiovascular annual meetings

Using a 1-page bar-coded food frequency questionnaire, the food habits of 996 adults who participated in diet screening at the annual meetings of the American Heart Association (1989) and the American College of Cardiology (1990) were analyzed for sex, age and regional differences. Estimated nutrient intakes were also compared with those from the Department of Agriculture's 1985 and 1986 Continuing Survey of Food Intake of Individuals. The average diet reported in this study satisfied National Cholesterol Education Program guidelines for cholesterol intake, but was higher than that recommended for total and saturated fats. In addition, dietary fat intake was influenced by sex, age and geographic region. Reduction in total and saturated fat intake was confined to men greater than 35 years of age; intake of these nutrients was highest among young, Mid-western women. These results suggest the need for diet intervention programs, targeted specifically to young adults with additional consideration given to regional variation. Repeated surveys of cardiac care givers might be used as an early indicator of the nationwide effectiveness of dietary intervention programs.

Evaluation of human panelists in assessing coronary atherosclerosis

The Cholesterol Lowering Atherosclerosis Study, a randomized, angiographic clinical trial, has demonstrated the beneficial effect of niacin/colestipol therapy on coronary and femoral atherosclerosis. The primary outcome was a panel-determined consensus score evaluating global coronary changes determined angiographically at 2 years. This article presents an evaluation of interreader agreement in independently assessing the status of native coronary arteries and overall coronary condition. Parameters include 1) identification of the presence of lesions and lesion changes; 2) estimation of lesion severity (percent stenosis) and amount of change in lesion severity; and 3) global assessment of change in coronary status. Readers independently agreed on 1) presence of lesions (82%) and change in lesions (51%); 2) percent stenosis +/- 10% (76%) and change in stenosis +/- 10% (81%); and 3) global assessment of change in coronary status within one step (96%). Results of these analyses may be useful in effectively designing angiographic trials that use a panel of human evaluators as well as computerized methods for angiographic interpretation.