Eugene M. Laska

Prevalence of Autism Spectrum Disorders in a Total Population Sample

OBJECTIVE Experts disagree about the causes and significance of the recent increases in the prevalence of autism spectrum disorders (ASDs). Limited data on population base rates contribute to this uncertainty. Using a population-based sample, the authors sought to estimate the prevalence and describe the clinical characteristics of ASDs in school-age children. METHOD The target population was all 7- to 12-year-old children (N=55,266) in a South Korean community; the study used a high-probability group from special education schools and a disability registry and a low-probability, general-population sample from regular schools. To identify cases, the authors used the Autism Spectrum Screening Questionnaire for systematic, multi-informant screening. Parents of children who screened positive were offered comprehensive assessments using standardized diagnostic procedures. RESULTS The prevalence of ASDs was estimated to be 2.64% (95% CI=1.91-3.37), with 1.89% (95% CI=1.43-2.36) in the general-population sample and 0.75% (95% CI=0.58-0.93) in the high-probability group. ASD characteristics differed between the two groups: the male-to-female ratios were 2.5:1 and 5.1:1 in the general population sample and high-probability group, respectively, and the ratios of autistic disorders to other ASD subtypes were 1:2.6 and 2.6:1, respectively; 12% in the general-population sample had superior IQs, compared with 7% in the high-probability group; and 16% in the general-population sample had intellectual disability, compared with 59% in the high-probability group. CONCLUSIONS Two-thirds of ASD cases in the overall sample were in the mainstream school population, undiagnosed and untreated. These findings suggest that rigorous screening and comprehensive population coverage are necessary to produce more accurate ASD prevalence estimates and underscore the need for better detection, assessment, and services.

Sarizotan as a treatment for dyskinesias in Parkinson's disease: a double-blind placebo-controlled trial.

The objective of this study is to conduct a dose‐finding study of sarizotan in Parkinsons disease (PD) patients with dyskinesia to identify a safe dose and to identify a sensitive dyskinesia rating measure. Sarizotan is a novel compound with full 5‐HT1A agonist properties and additional high affinity for D3 and D4 receptors. An open label study documented improvements in PD patients with levodopa‐induced dyskinesia. There is no precedent for study designs or outcome measures in pivotal trials of antidyskinesia therapies. The approach used here was a multicenter, randomized, placebo‐controlled, double‐blind, parallel study. Included were PD patients optimized to levodopa and dopaminergic drugs with moderately disabling dyskinesias present greater than or equal to 25% of the waking day. Interventions included sarizotan 2, 4, or 10 mg/day or matching placebo, given in two doses. There were two outcome measures: the primary measure was change from baseline in diary‐based on time without dyskinesia; the secondary measures were change from baseline in scores on the Abnormal Involuntary Movement Scale (AIMS), the composite score of Unified Parkinsons Disease Rating Scale (UPDRS) Items 32+33 (dyskinesia duration and disability) and total UPDRS. A total of 398 subjects were randomized, with 381 included in the intention‐to‐treat population. No significant changes occurred on sarizotan compared to placebo on any diary‐based measure of dyskinesia or the AIMS score. The composite score of UPDRS Items 32+33 was significantly improved with 2 mg/day sarizotan, with a trend at 10 mg/day. Adverse events were not significantly different in sarizotan‐ and placebo‐treated patients, but off time significantly increased with sarizotan 10 mg/day. Sarizotan 2 mg/day is a safe agent in PD patients with dyskinesia. To test its role in abating dyskinesia, future studies should focus on this dose and will use the composite score of UPDRS Items 32+33 as the primary outcome.

The correlation between blood levels of ibuprofen and clinical analgesic response

A clinical trial comparing ibuprofen, 400, 600, and 800 mg, with aluminum ibuprofen, 400 mg, and placebo was conducted in patients with moderate or severe pain subsequent to third molar extraction. Pain intensity ratings and ibuprofen serum levels were obtained at baseline, 30 minutes, 1 hour, and hourly thereafter for 3 hours. Pain intensity ratings were also obtained at hours 4, 5, and 6. Serum levels at 1, 2, and 3 hours correlated significantly with the log dose of ibuprofen (r = 0.35, 0.49, and 0.48, respectively) and with global analgesic response as measured by the percentage of the sum of the pain intensity scores (r = 0.28, 0.34, and 0.26, respectively). However, possibly because of differences in drug formulation, the percentage of the sum of the pain intensity scores did not correlate significantly with log dose. The highest correlations were found between contemporaneous serum levels and pain intensity difference values, particularly at hour 1 (r = 0.54). Our results support the proposition that increased ibuprofen serum levels lead to increased analgesia.

Hippocampal hypometabolism predicts cognitive decline from normal aging.

OBJECTIVE This longitudinal study used FDG-PET imaging to predict and monitor cognitive decline from normal aging. METHODS Seventy-seven 50-80-year-old normal (NL) elderly received longitudinal clinical examinations over 6-14 years (561 person-years, mean per person 7.2 years). All subjects had a baseline FDG-PET scan and 55 subjects received follow-up PET exams. Glucose metabolic rates (MRglc) in the hippocampus and cortical regions were examined as predictors and correlates of clinical decline. RESULTS Eleven NL subjects developed dementia, including six with Alzheimers disease (AD), and 19 declined to mild cognitive impairment (MCI), on average 8 years after the baseline exam. The baseline hippocampal MRglc predicted decline from NL to AD (81% accuracy), including two post-mortem confirmed cases, from NL to other dementias (77% accuracy), and from NL to MCI (71% accuracy). Greater rates of hippocampal and cortical MRglc reductions were found in the declining as compared to the non-declining NL. CONCLUSIONS Hippocampal MRglc reductions using FDG-PET during normal aging predict cognitive decline years in advance of the clinical diagnosis. Future studies are needed to increase preclinical specificity in differentiating dementing disorders.

Testing Whether an Identified Treatment Is Best

We consider the problem of testing whether an identified treatment is better than each of K treatments. Suppose there are univariate test statistics Si that contrast the identified treatment with treatment i for i = 1, 2,...., K. The min test is defined to be the alpha-level procedure that rejects the null hypothesis that the identified treatment is not best when, for all i, Si rejects the one-sided hypothesis, at the alpha-level, that the identified treatment is not better than the ith treatment. In the normal case where Si are t statistics the min test is the likelihood ratio test. For distributions satisfying mild regularity conditions, if attention is restricted to test statistics that are monotone nondecreasing functions of Si, then regardless of their covariance structure the min test is an optimal alpha-level test. Tables of the sample size needed to achieve power .5, .8, .90, and .95 are given for the min test when the Si are Students t and Wilcoxon.

Reproducibility of cerebral glucose metabolic measurements in resting human subjects.

Positron emission tomography with 11C-2-deoxyglucose was used to determine the test-retest variability of regional cerebral glucose metabolism in 22 young normal right-handed men scanned twice in a 24-h period under baseline (resting) conditions. To assess the effects of scan order and time of day on variability, 12 subjects were scanned in the morning and afternoon of the same day (a.m.-p.m.) and 10 in the reverse order (p.m.-a.m.) with a night in between. The effect of anxiety on metabolism was also assessed. Seventy-three percent of the total subject group showed changes in whole brain metabolism from the first to the second measurement of 10% or less, with comparable changes in various cortical and subcortical regions. When a scaling factor was used to equate the whole brain metabolism in the two scans for each individual, the resulting average regional changes for each group were no mote than 1%. This suggests that the proportion of the whole brain metabolism utilized regionally is stable in a group of subjects over time. Both groups of subjects had lower morning than afternoon metabolism, but the differences were slight in the p.m.-a.m. group. One measure of anxiety (pulse at fun 1) was correlated with run 1 metabolism and with the percentage of change from run 1 to run 2. No significant run 2 correlations were observed. This is the first study to measure test-retest variability in cerebral glucose metabolism in a large sample of young normal subjects. It demonstrates that the deoxyglucose method yields low Intrasubject variability and high stability over a 24-h period.

Optimal crossover designs in the presence of carryover effects.

Under either the random patient-effect model with sequence effects or the fixed patient-effect model, the usual two-period, two-treatment crossover design, AB,BA, cannot be used to estimate the contrast between direct treatment effects when unequal carryover effects are present. If baseline observations are available, the design AB,BA can validly be used to estimate a treatment contrast. However, the design AB,BA,AA,BB with baseline observations is more efficient. In fact, we show that this design is optimal whether or not baseline observations are available. For experiments with more than two periods, universally optimal designs are found for both models, with and without carryover effects. It is shown that uncertainty about the presence of carryover effects is of little or no consequence, and the addition of baseline observations is of little or no added value for designs with three or more periods; however, if the experiment is limited to only two periods the investigator pays a heavy penalty.

Effect of caffeine on acetaminophen analgesia

Our objective was to determine the value of caffeine in combination with acetaminophen in the relief of pain from uterine cramping, episiotomy, and third molar extraction. In the dental study, 173 patients received two or four tablets of 500 mg acetaminophen or the combination of 500 mg acetaminophen and 65 mg caffeine. In the three postpartum studies, 1345 patients received one, two, or three tablets of acetaminophen, the combination, or a placebo. The mean scores for the summary variable percent sum of the pain intensity differences (% SPID) were higher in all for the combination than for acetaminophen alone, and in two studies the null hypothesis of no differences was rejected. The relative potency estimates for % SPID were 1.9, 1.8, and 1.3 for the three studies in which bioassays could be performed and the pooled relative potency was 1.7 with a 95% confidence interval of 1.1 to 3.1. The results were essentially the same among pain models and among patient groups with similar habitual caffeine consumption. Onset of analgesia was also faster with the combination. We conclude that caffeine enhances the analgesic efficacy of acetaminophen.

Placebo influences on dyskinesia in Parkinson's disease

Clinical features that are prognostic indicators of placebo response among dyskinetic Parkinsons disease patients were determined. Placebo‐associated improvements occur in Parkinsonism, but responses in dyskinesia have not been studied. Placebo data from two multicenter studies with identical design comparing sarizotan to placebo for treating dyskinesia were accessed. Sarizotan (2 mg/day) failed to improve dyskinesia compared with placebo, but both treatments improved dyskinesia compared with baseline. Stepwise regression identified baseline characteristics that influenced dyskinesia response to placebo, and these factors were entered into a logistic regression model to quantify their influence on placebo‐related dyskinesia improvements and worsening. Because placebo‐associated improvements in Parkinsonism have been attributed to heightened dopaminergic activity, we also examined the association between changes in Parkinsonism and dyskinesia. Four hundred eighty‐four subjects received placebo treatment; 178 met criteria for placebo‐associated dyskinesia improvement and 37 for dyskinesia worsening. Older age, lower baseline Parkinsonism score, and lower total daily levodopa doses were associated with placebo‐associated improvement, whereas lower baseline dyskinesia score was associated with placebo‐associated worsening. Placebo‐associated dyskinesia changes were not correlated with Parkinsonism changes, and all effects in the sarizotan group were statistically explained by the placebo‐effect regression model. Dyskinesias are affected by placebo treatment. The absence of correlation between placebo‐induced changes in dyskinesia and Parkinsonism argues against a dopaminergic activation mechanism to explain placebo‐associated improvements in dyskinesia. The magnitude and variance of placebo‐related changes and the factors that influence them can be helpful in the design of future clinical trials of antidyskinetic agents.

Statistical inference for cost-effectiveness ratios.

Methods for statistical inference for cost-effectiveness (C/E) ratios for individual treatment and for incremental cost-effectiveness (delta C/ delta E) ratios when two treatments are compared are presented. In a lemma, we relate the relative magnitude of two C/E ratios to the delta C/ delta E ratio. We describe a statistical procedure to test for dominance, or admissibility, that can be used to eliminate an inferior treatment. The one-sided Bonferronis confidence interval procedure is generalized to the two-sided case. The method requires only that two confidence intervals be available, one for cost and one for effectiveness. We describe Fieller-based confidence intervals and show them to be shorter than Bonferroni intervals. When distribution assumptions hold and variance and covariance estimates are available, Fieller intervals are preferable. However, Bonferroni intervals can be applied in more diverse situations and are easier to calculate. A simple Bonferroni based technique, and a likelihood ratio statistic given by Siegel, Laska and Meisner, for testing the null hypothesis that the C/E ratios of two treatments are equal is presented. The approaches are applied to the data from a phase II clinical trial of a new treatment for sepsis considered previously by others.