Self-observation, self-analysis, and reanalysis. Panel report.
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The Turlock vitamin-mineral supplementation trial: a statistical reanalysis.
A new analysis of a randomised double-blind trial confirms the fact that vitamin-mineral supplementation has a statistically significant effect on non-verbal IQ as measured by the WISC-R test. Further studies may show if this effect is large enough to be of practical importance.
Adolescent↗
Hypertensive episode associated with phenelzine and tap beer--a reanalysis of the role of pressor amines in beer.
A case report of a hypertensive crisis resulting from the ingestion of tap beer in a patient on an irreversible monamine oxidase inhibitor (MAOI; phenelzine) stimulated the investigation of different kinds of beer for tyramine concentration. The objective was to determine the tyramine concentration in tap and bottled beers. A total of 98 beer samples (79 different brands of beer) were analyzed by high-performance liquid chromatography for tyramine. Of these 98 beers, 49 were bottled or canned beers and 49 were beers on tap. All of the bottled beers analyzed had safe tyramine concentrations (< or = 10 mg/liter; range, 0 to 3.16 mg/liter) and, thus, do not require restriction in patients receiving MAOIs. Therefore, the consumption of canned or bottled beer, including dealcoholized beer, in moderation (fewer than four bottles or cans; 1.5 liters within a 4-hour period) appears to be safe and does not require restriction in patients receiving MAOIs. Only 4 of 98 beer samples studied were found to have a dangerous (> 10 mg/liter) tyramine concentration, one of which was the index beer. The tyramine concentration in these four beers ranged from 26.34 to 112.91 mg/liter. All four of these beers were tap beers produced by bottom fermentation (lagers) and brewed by a secondary fermentation process. Although we did not find any visible bacterial growth in the tap beers with high tyramine content, this finding does not preclude the possibility that bacterial contamination, bacterial growth, production of tyramine, and eventually bacterial death occurred at some earlier time. Therefore, to err on the side of caution, it is recommended that patients on irreversible MAOIs avoid beers on tap.
Adult↗
Reanalysis of forensic urine specimens containing benzoylecgonine and THC-COOH.
Drug testing laboratories are often requested to retest specimens that have tested positive. The reproducibility of analytical retest data for delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) and benzoylecgonine in specimens that had previously been analyzed and then frozen by the Navy Drug Screening Laboratory, Great Lakes is examined in this study. All specimens were tested by gas chromatography/mass spectrometry (GC/MS). Retest values generally showed a decrease in concentration but exhibited considerable variability. Eighty-five THC-COOH positive urine specimens stored frozen for 1 to 10 months (average 2.3 months) declined an average of 25% (range, +30% to -80%) and 61 benzoylecgonine positive urine specimens stored for 1 to 8 months (average 2.3 months) declined an average of 19% (ranged +20% to -100%) from initial GC/MS test results. Drugs were found to partition into strata when frozen in urine because of the thermodynamics of the freezing process. To assure a homogenous solution for repeat testing, specimens that have been frozen and thawed were gently mixed before analysis.
Bias↗
A reanalysis of the Cu-7 intrauterine contraceptive device clinical trial and the incidence of pelvic inflammatory disease: a paradigm for assessing intrauterine contraceptive device safety.
OBJECTIVE: We calculated and compared the incidence of pelvic inflammatory disease in a 10% random sample of the Cu-7 intrauterine contraceptive device (G.D. Searle & Co., Skokie, Ill.) clinical trial with the rates reported to the Food and Drug Administration and those in subsequent trials published in the world literature. STUDY DESIGN: A 10% random sample of the Cu-7 clinical trial was examined because calculations had demonstrated this random sample to be sufficient in size (n = 1614) to detect a difference in rates of pelvic inflammatory disease from those reported to the Food and Drug Administration. An audit of a subset of the patient files, compared with the original files in Skokie, Illinois, confirmed that the files available for analysis were complete. Standard definitions were used to identify cases of pelvic inflammatory disease and to calculate rates of pelvic inflammatory disease. The world literature on Cu-7 clinical trials was reviewed. RESULTS: The calculated crude and Pearl index rates of pelvic inflammatory disease were consistent with those rates previously reported to the Food and Drug Administration and published in the medical literature. Life-table pelvic inflammatory disease rates were not different between nulliparous and parous women and pelvic inflammatory disease did not differ from basal annual rates in fecund women. CONCLUSION: On the basis of the analysis of this 10% sample, the pelvic inflammatory disease patient rates reported to the Food and Drug Administration for the entire Cu-7 clinical trial are accurate and are similar to those published in the world literature.
Adult↗
Circannual pattern of autistic births: reanalysis in three ethnic groups.
Seasonal variations in births of autistic subjects have been reported for the United States, Canada, Sweden, Japan, and Israel. Here, data from England, Japan, and Israel are reanalyzed using spectral analysis for the cosine function. A sample of 583 autistic births occurring over 40 years (1947-1989) is meta-analyzed, focusing on rhythmicity. Major periodicities of 17.6, 18.6, and 21.8 years, on which minor periodicities ranging from 2.2 to 4.1 years were superimposed, yielded the best-fitting cosine function to significantly explain variance of autistic birth patterns. It is interesting that the function composed of a major period with several minor periods is remarkably similar in each of the three ethnic groups. In all three countries the acrophases (calculated function) aggregate in the period 1963-1970. In light of this apparent universality of rhythms in autistic births across continents, we call for further investigations into the role of environmental factors, possibly viral pandemics, in the etiology of autism.
Autistic Disorder↗
Reanalysis of existing trial data: what can be learned.
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Anticonvulsants↗
Reanalysis of some baboon descent data.
Wagner and Altmann [1973] recently reported an analysis of a set of baboon descent times, some of which were left censored due to varying arrival times at the observation site. Any transformation of the data which reverses order produced a set of right censored observations. In this way, the Kaplan-Meier [1958] estimate of the descent time distribution can be computed. Estimates of the mean and variance of the distribution are given, as well as the standard error of the estimate of the mean.
Animals↗
Effect of a ketoacid-aminoacid-supplemented very low protein diet on the progression of advanced renal disease: a reanalysis of the MDRD feasibility study.
BACKGROUND: We reanalyzed the data of the Modification of Diet in Renal Disease (MDRD) feasibility study to ascertain the effects of ketoacid- and aminoacid-supplemented very low protein diets. METHODS: Sixty-six patients with advanced renal disease (Study B, baseline glomerular filtration rate (GFR) 7.5-24 ml/min/1.73 m2) were randomly assigned to a low protein diet (L, 0.575 g/kg/d), or a very low protein diet (0.28 g/kg/d) supplemented either with a ketoacid-aminoacid mixture (diet K) or with a mixture of essential aminoacids (diet J). Thirty patients with moderate renal disease (Study A, baseline GFR 25-80 ml/min/1.73 m2) were randomly assigned to a usual protein diet (M, 1.2 g/kg/d), diet L, or diet K. Mean follow-up was 14 months. RESULTS: In Study B, GFR decline differed among the three diets (p = 0.028). Pairwise comparisons showed that the mean +/- SE GFR decline in ml/min/mo in diet K [-0.250+/-0.072] was slower than in diet J [-0.533+/-0.074] (p = 0.008) despite similar achieved protein intakes. The mean GFR decline in diet L [-0.394+/-0.068] was intermediate between, and did not differ significantly from the rates of decline in the other two groups. In Study A, consistent with a hemodynamic effect, the mean GFR decline varied directly with the reduction in protein intake in diets M, L and K (p = 0.028) during the first four months of follow-up, but thereafter did not differ among the diet groups (p = 0.76). CONCLUSION: The study suggests that supplementation of a very low protein diet with the ketoacid-aminoacid mixture used in this feasibility study slowed the progression of advanced renal disease more than supplementation with an amino acid mixture.
Adult↗
[Psychotherapy research--how it should (not) be done. An expert reanalysis of comparative studies by Grawe et al. (1994)].
22 psychotherapy outcome studies used in the Bernese meta-analysis by Grawe, Donati and Bernauer (1994) for a treatment comparison between behavioural and psychoanalytic-psychodynamic treatment concepts were reanalysed by 12 expert psychotherapy researchers independent of each other. Three clinical criteria served as basic criteria for the assessment of the methodological quality of the 22 comparative studies: treatment dosage, therapists' competence or expertise, and an adequate realisation of the intended treatment concept. The expert ratings were then compared with an evaluation of an assessment of a research team from the University of Ulm and with the one from the Bernese research team. Contrary to the Bernese meta-analysis, both the experts and the Ulm research group conclude that only 5 or 8 of the 22 studies, respectively, could be accepted for a relatively fair comparison between the treatments under study. Out of the 5/8 studies, none could be considered fully suitable for a treatment comparison, at the most only moderately suitable. These remaining 5 or 8 studies, respectively, do not prove superiority of one treatment over the other. Hence, the "Dodo Bird Verdict" stands up under scrutiny.
Behavior Therapy↗
Methods for comparison of cost data.
BACKGROUND: Researchers are increasingly interested in examining costs of care, and large administrative and clinical databases have made relevant data readily available. Because a few patients incur high costs relative to most patients, the distribution of cost data is often skewed. How robust are the usual methods of cost analysis against the skewed distribution of cost data? OBJECTIVE: To determine the methods commonly used for comparing cost data, describe their limitations, and provide an alternate method of analysis. DESIGN: Review of statistical methods used in studies of medical costs published in medical journals between January 1991 and January 1996. Description of a Z-score method appropriate for testing the equality of mean costs between two log-normal samples; and reanalysis of published two-sample comparison results done by using the Z-score method. RESULTS: For two-sample comparisons, three methods were commonly used: the Student t-test on untransformed costs, the Wilcoxon test on untransformed costs, and the Student t-test on log-transformed costs. The t-test on untransformed costs ignores the skewness in cost data, the Wilcoxon test ignores unequal variances, and the t-test on log-transformed costs tests the wrong null hypothesis unless variances in the log-scale are equal. Eleven articles included two-sample tests and had enough information to allow reanalysis of the data using the Z-score method. These articles described a total of 23 Wilcoxon tests and 24 t-tests on untransformed costs. Most results did not change on reanalysis, but six results changed enough to alter conclusions. Specifically, reanalysis of data for which one Wilcoxon test had shown statistically significant results showed nonsignificant results; reanalysis of data for which two Wilcoxon tests had shown nonsignificant results showed statistically significant results. In articles that used t-tests on untransformed costs, two statistically significant results became nonsignificant on reanalysis and one nonsignificant result became statistically significant on reanalysis. CONCLUSIONS: The methods commonly used to compare costs of two groups have limitations. Some limitations may change some conclusions, and the direction of the change cannot be predicted. The Z-score method is designed to adjust for skewness in cost data and is appropriate for comparing means of log-normally distributed cost data.
Costs and Cost Analysis↗
The association between sulfate air pollution and mortality at the county scale: an exploration of the impact of scale on a long-term exposure study.
The American Cancer Society (ACS) Study and its reanalysis are built upon in order to examine the impact of scale on the observed relationship between sulfates and mortality. The limitations of the original ACS Study (Pope et al., 1995) and the reanalysis of this study (Krewski et al., 2000) are discussed; while the latter dealt with some issues in using ecological data, it did not address scale. Next, the article outlines the county-scale study, the methods used to aggregate data, and the two-stage analysis used to derive relative risk (RR). Finally, the results of working at the county scale are compared with those obtained by the reanalysis team using larger metropolitan areas. Less than half of the cohort used in the metropolitan study were used at the county scale because of the limited availability of sulfate monitors and because five-digit ZIP codes more accurately assigned individuals to geographical areas. Therefore, the county data should be considered as new and not as a reorganization of the original data set. The reanalysis and the county studies should be considered as two separate studies that took different scales as their basic organizing principle. The RR of all-cause mortality from sulfate exposure at the county scale was 1.50 (1.30, 1.73) compared with 1.25 (1.13, 1.37) at the metropolitan scale; for cardiopulmonary mortality, the RR was 1.75 (1.48, 2.08) at the county scale compared with 1.29 (1.15, 1.46) at the metropolitan scale. Because lung cancer mortality was low in some counties, the two-stage random effects model became unstable. At the county scale, the RR from sulfates was more robust to the inclusion of ecologic covariates. Other place-specific ecologic covariates were either insignificant or barely significant (with a lower 95% confidence limit near 0.99 or 1.00) when included in the two-stage regression model for all-cause mortality with sulfates. Moreover, no ecologic covariate changed the RR of all-cause mortality from sulfates by 25% or more. Both population change and unemployment rate affected the RR for cardiopulmonary mortality from sulfate exposure by 25% or more in the county-scale analysis. However, when these two variables were entered into a multiple covariate analysis, the RR from sulfates decreased but remained strongly significant. Sulfur dioxide was not an important covariate at the county scale. Thus, at the county scale, long-term exposure to sulfates appears to be more strongly associated with increased risk of all-cause and cardiopulmonary mortality than previously indicated by the ACS study and its reanalysis.
Air Pollution↗
Context-sensitive neural responses to conflict resolution: electrophysiological evidence from subject-object ambiguities in language comprehension.
Reanalysis in language comprehension provides a window on how superficially similar processes of conflict resolution may differ depending on the context in which they are initiated. Thus, previous ERP studies have shown that reanalyses towards object-initial orders in German sentences with dative-active verbs (e.g., folgen, 'to follow') engender N400 effects, while reanalyses with accusative verbs (e.g., besuchen, 'to visit') elicit P600 effects. This difference appears surprising since these two verb classes are both associated with a subject-initial base order. The present paper reports two ERP experiments designed to shed further light on the nature of the conflict resolution processes involved in each case by examining structures in which word order disambiguation is separated from verb class disambiguation. Experiment 1 contrasted dative-active verbs with accusative verbs, while Experiment 2 compared dative-active and dative object-experiencer verbs (which are associated with an object-initial base order). Our results show that the reanalysis pattern for dative-active constructions is context-dependent: when verb class disambiguation precedes word order disambiguation, an N400-P600 pattern results. By contrast, the reanalysis patterns for the other two verb types are context independent: object-experiencer verbs invariably show an N400 and accusative verbs invariably show a P600. We argue that (a) the N400 is a general marker of reanalysis in dative sentences, reflecting an argument reindexation, while (b) the P600 in accusative sentences reflects a structural recomputation. The variable pattern for dative-active sentences reflects the (in)applicability of "good-enough" representations during conflict resolution in garden path sentences.
Adult↗
Alteplase and ischaemic stroke: have new reviews of old data helped?
BACKGROUND: Thrombolysis for stroke is still not widely used as current recommendations restrict treatment to selected patients. In general, these are patients who can be assessed quickly by specialised stroke teams, have intracranial haemorrhage excluded by appropriate brain imaging, and are treated with alteplase (recombinant tissue plasminogen activator; rt-PA) within 3 h of symptom onset. There is, however, still much debate regarding the scope of treatment and the reorganisation of services required to support an effective service. RECENT DEVELOPMENTS: Two recent publications have helped clarify some issues. The first was an individual-patient data meta-analysis of the alteplase trials. These analyses suggest treatment effects beyond the usual 3 h time window, but other than time to treatment no other factors influenced the effects of treatment. The second publication was a reanalysis of the original National Institute of Neurological Disorders and Stroke (NINDS) alteplase trial, done after criticism of the original study. The reanalysis confirmed that there was significant baseline imbalance of stroke severity between treatment and control groups in the NINDS trial, but established that this did not materially affect the positive results of the trial. However, the recording of blood pressure in the study was found to be inconsistent and therefore unsuitable for reanalysis. The previously published data on recommendations for blood-pressure control, arising from the NINDS trial, needs to be reconsidered in this light. Both studies included too few patients to provide reliable data on which clinical and radiological features influence the response to alteplase. WHERE NEXT?: The individual-patient data meta-analysis and reanalysis of the NINDS trial have probably exhausted the potential of previous trials to answer questions on the effects of thrombolysis. Further randomised trials comparing thrombolysis with control will be required to determine whether elderly people benefit from treatment or whether there are worthwhile benefits from alteplase beyond 3 h (and in such patients, whether advanced magnetic resonance imaging is an effective way to select those most likely to benefit). Various new approaches to reperfusion also require assessment in large-scale trials: new thrombolytic drugs, the combination of intravenous and intra-arterial thrombolytic drugs, combinations of thrombolytics with new antiplatelet agents, and augmentation of thrombolysis either with mechanical devices or with transcranial ultrasound.
Fibrinolytic Agents↗
Falsifying serial and parallel parsing models: empirical conundrums and an overlooked paradigm.
When the human parser encounters a local structural ambiguity, are multiple structures pursued (parallel or breadth-first parsing), or just a single preferred structure (serial or depth-first parsing)? This note discusses four important classes of serial and parallel models: simple limited parallel, ranked limited parallel, deterministic serial with reanalysis, and probabilistic serial with reanalysis. It is argued that existing evidence is compatible only with probabilistic serial-reanalysis models, or ranked parallel models augmented with a reanalysis component. A new class of linguistic structures is introduced on which the behavior of serial and parallel parsers diverge the most radically: multiple local ambiguities are stacked to increase the number of viable alternatives in the ambiguous region from two to eight structures. This paradigm may provide the strongest test yet for parallel models.
Humans↗
Effect of population density on the results of the study of water supplies in five California counties.
Two previous studies (1969-1971 and 1969-1974) examined the association between cancer incidence and chrysotile asbestos ingested through drinking water in the San Francisco-Oakland Standard Metropolitan Statistical Area (SMSA). Population density, an important covariable in the association between cancer and environmental agents, was not included in the analyses of these studies. The present work determines the effect of this covariable on the results of the second San Francisco-Oakland SMSA study. The original and reanalyzed results are compared to reassess the association between cancer and asbestos. The only change in the regression procedures of the original studies was the addition of population density as an independent variable in the reanalysis. The results of the reanalysis showed that population density had little effect on the results of the second study. Slightly more significance was found for asbestos regression coefficients in the reanalysis, including population density, than in the original analysis. These regression coefficients for asbestos indicated a positive association between ingested chrysotile asbestos and some cancer body sites. The conclusion of the reanalysis was that population density was distributed across the San Francisco-Oakland SMSA in such a way that it had little effect on the observation of an association between ingested asbestos and cancer.
Asbestos↗
Flow cytometric sorting of non-human primate sperm nuclei.
Pre-determination of the sex of offspring has implications for management and conservation of captive wildlife species, particularly those with single sex-dominated social structures. Our goal is to adapt flow cytometry technology to sort spermatozoa of non-human primate species for use with assisted reproductive technologies. The objectives of this study were to: (i) determine the difference in DNA content between X- and Y-bearing spermatozoa (ii) sort sperm nuclei into X- and Y-enriched samples; and (iii) assess the accuracy of sorting. Spermatozoa were collected from two common marmosets (Callithrix jacchus), seven hamadryas baboons (Papio hamadryas) and two common chimpanzees (Pan troglodytes). Human spermatozoa from one male were used as a control. Sperm nuclei were stained (Hoechst 33342), incubated and analyzed using a high-speed cell sorter. Flow cytometric reanalysis of sorted samples (sort reanalysis, 10,000 events/sample) and fluorescence in situ hybridization (FISH; 500 sperm nuclei/sample) were used to evaluate accuracy of sorting. Based on fluorescence intensity of X- and Y-bearing sperm nuclei, the difference in DNA content between X and Y populations was 4.09 +/- 0.03, 4.20 +/- 0.03, 3.30 +/- 0.01, and 2.97 +/- 0.05%, for marmoset, baboon, chimpanzee and human, respectively. Sort reanalysis and FISH results were similar; combined data revealed high levels of purity for X- and Y-enriched samples (94 +/- 0.9 and 93 +/- 0.8%, 94 +/- 0.7 and 94 +/- 0.5%, 91 +/- 0.9 and 97 +/- 0.6%, 94 +/- 0.6 and 94 +/- 0.9%, for marmoset, baboon, chimpanzee and human, respectively). These data indicate the potential for high-purity sorting of spermatozoa from non-human primates.
Animals↗
Morehead & Ingram (1973) revisited.
The finding in Morehead and Ingram (1973) that children with a language impairment do better in the use of inflectional morphology than MLU-matched typically developing children has been in marked contrast to several subsequent studies that have found the opposite relationship (cf. review in Leonard, 1998). This research note presents a reanalysis of a subset of the original Morehead and Ingram data in an attempt to reconcile these contradictory findings. The reanalysis revealed that the advantage on inflectional morphology for children with language impairment was only on the progressive suffix, not on plural and possessive or on the verbal morphemes third-person present tense and past tense. The results of the reanalysis are in line with more recent research (e.g., Rice, Wexler, & Cleave, 1995). The resolution of these discrepant results highlights the critical roles that methodological issues play--specifically, how subjects are matched on MLU, how inflectional morphology is measured, and the selection of subjects with regard to age.
Child↗