Prognostic significance of p53 mutations in non-small cell lung cancer: a meta-analysis of 829 cases from eight published studies.

Mutation of the p53 tumor suppressor gene is considered a possible marker of poor survival among patients with non-small cell lung cancer (NSCLC). This report presents the results of a meta-analysis of the available data addressing this issue. Using previously described methods, a protocol was developed for a meta-analysis examining the prognostic significance of p53 mutations in NSCLC. Two-year survival data derived from 829 patients in eight published studies were analyzed using a general variance-based method employing confidence intervals described by Greenland (Epidemiol. Rev. 9 (1986) 1-30). The outcome of interest was a summary relative risk (RRs) reflecting the risk of death at 2 years associated with p53 mutation positive versus p53 negative disease. Prior to calculation of a RRs, an analysis for homogeneity (Q) showed Q to equal 22.3. With 8 degrees of freedom, this yielded a P value corresponding to P<0.005. This indicated substantial heterogeneity across studies in terms of their estimate of effect. Although a RRs of 1.52 was found when all eight studies were combined (favoring a negative prognostic role for p53 mutation), the validity of this estimate is questionable since the existing heterogeneity indicates that factors other than p53 mutation account for the variability in RRs across studies. Sensitivity analyses suggested that selection bias might represent an important source of variability in that p53 mutations may differ in their effects on biological behavior of NSCL tumors. Other possible confounders include smoking history, race, geographic location of study and socio-economic status. The available data do not support a clear role for p53 mutation as a prognostic marker in NSCLC. It appears that multiple sources of bias may contribute to spurious association of p53 mutation status and survival. Future analyses must control for possible confounders in order to determine whether certain p53 mutations are truly associated with poor clinical outcome.

Risk of serious adverse events in hypertensive patients receiving isradipine: a meta-analysis.

A meta-analysis was performed to compare the risk of serious adverse events associated with the use of all formulations of isradipine, when used as monotherapy in hypertension, to active drug or placebo controls. Eligible studies totalled 65 published and unpublished randomised controlled trials involving 9903 subjects and 10,675 treatment exposures: 4492 to isradipine, 1473 to isradipine sustained release, 2768 to other active drugs, and 1942 to placebo. Mortality, cardiovascular outcomes, other serious incident illnesses, such as cancer, and withdrawals were sought. Seventy-five per cent of the isradipine exposures were to standard-release formulations and 25% were to sustained-release formulations. Overall, isradipine therapy shows no difference in risk of major adverse events or withdrawals compared to other active controls or placebo (odds ratios [OR] 0.9; 95% CI 0.7-1.46 and 0.5; 95% CI 0.2-1.3). These major adverse events included angina, fatal and non-fatal myocardial infarction, stroke and overall mortality. Isradipine sustained release could be compared only to placebo, based on available data, and shows a lower risk of withdrawals (OR 0.5; 95% CI 0.3-0.9), and a similar trend was observed for major adverse events, (OR 0.8; 95% CI 0.3-2.5). Published and unpublished randomised controlled trials were analysed in separate meta-analyses and later combined when this sensitivity analysis of risk showed no differences between the groups. In conclusion, we find no evidence for increased risk of serious adverse events in patients receiving isradipine as monotherapy for hypertension.

A systematic review and meta-analysis of the incidence of cancer in randomized, controlled trials of verapamil.

We conducted a systematic review of all published randomized, controlled trials to assess the risk of cancer or death in patients receiving verapamil for hypertension, angina pectoris, or cardiac arrhythmias. Meta-analysis comparing the risk of new cancers, cancer deaths, and all deaths was performed. Thirty-nine trials comprising 11,201 patients were eligible. Study durations ranged from 8 days-6 years (mean 29.5 wks). Nine trials (6507 patients) were 24 weeks in duration or longer. For cancer and cancer death, OR was 1.20 (95% CI = 0.60-2.42) for verapamil versus active controls and 0.73 (95% CI = 0.39-1.39) for verapamil versus placebo. For all deaths, OR was 1.13 (95% CI = 0.70-1.82) for verapamil versus active controls and 0.85 (95% CI = 0.71-1.00) for verapamil versus placebo. Sensitivity analysis for the 9 trials 24 weeks' duration or longer gave similar results. There is no statistically significant increased risk of cancer or deaths with verapamil compared with active controls or placebo.

Epidermal growth factor receptor gene amplification as a prognostic marker in glioblastoma multiforme: results of a meta-analysis.

Amplification of the epidermal growth factor receptor (EGFR) gene occurs in approximately 40% of cases of glioblastoma multiforme (GBM) and is considered a possible marker of poor prognosis. This report presents the results of a meta-analysis of the available data addressing this issue. Using a prospective protocol, a meta-analysis was designed to assess the possible prognostic importance of EGFR gene amplification in GBM. One-year survival data derived from seven published studies were analyzed using a general variance based method employing confidence intervals described by Greenland. The outcome of interest was a summary relative risk (RRs) reflecting the risk of death at 1 year from diagnosis associated with EGFR amplification-positive versus -negative disease. Prior to calculation of a RRs, an analysis for homogeneity (Q) showed Q to equal 9.21. With 6 df this yielded a P value of 0.12, indicating that the data were homogenous and could be combined in a meta-analysis. Pooling all available studies gave a RRs of 1.13 with a 95% confidence interval of 0.71-1.80, a nonstatistically significant result. The data suggest that the available studies are insufficient for determining whether EGFR gene amplification is of prognostic value in GBM. Important potential confounding factors are the influence of underlying EFGR gene mutation on patient survival and lack of control for important known clinical prognostic indicators in many studies. Future work must incorporate these parameters in multivariate analyses to determine whether EGFR gene alterations are truly associated with poor clinical outcome.

Impact of intravesical chemotherapy on recurrence rate of recurrent superficial transitional cell carcinoma of the bladder: results of a meta-analysis.

BACKGROUND: The impact of in tranvesical chemotherapy on preventing recurrence of superficial transitional cell carcinoma of the bladder is controversial. The objective of this report is to present a meta-analysis of the available clinical trial data to quantify the effect of intravesical chemotherapy on tumor recurrence following trans-urethral resection (TURB) in patients with recurrent superficial bladder cancer. METHODS: A prospective study protocol outlining a meta-analysis was developed followed by a thorough search of the existing published literature using strict eligibility criteria. Eight randomized trials were found which met protocol specifications. These studies contained data on 1,609 patients which were statistically combined using a fixed effects model (Peto). The outcome of interest was the proportion of patients with tumor recurrence at one, two and three years post-TURB. RESULTS: Combining all 8 studies using 1 year recurrence as the outcome measure yielded a Peto odds ratio (ORp) of 0.62, demonstrating a 38% reduction in one year recurrence among patients treated with intravesical chemotherapy versus TURB alone. Using 2 and 3 year recurrence as the outcome measure yielded ORp's of 0.46 and 0.35 respectively, favoring TURB + intravesical chemotherapy versus TURB alone. A statistical test for heterogeneity (Q) showed the 2 and 3 year outcome data to be heterogeneous (i.e. the studies are not measuring an effect of the same magnitude). Sensitivity analyses showed that drug type appeared to account for the observed heterogeneity with a stratified analysis demonstrating that adriamycin is less effective in reducing subsequent tumor recurrences than all other drugs studied. CONCLUSION: Intravesical chemotherapy appears to have a major impact on decreasing the chance of recurrence of recurrent superficial bladder cancer. Three year recurrence is decreased by as much as 70% when compared with TURB alone. These data are in contrast to prior analyses suggesting only modest efficacy of such treatment in this clinical setting.

Meta-analysis: an update.

A fairly new type of research, termed meta-analysis, attempts to analyze and combine the results of previous reports. In 1992 we updated our 1987 survey of 86 meta-analyses of randomized control trial reports in the english language literature with an additional 78. We evaluated the quality of these meta-analyses using a scoring method that lists 23 items in six major areas: study design, combinability, control of bias, statistical analysis, sensitivity analysis, and application of results. Of the 23 individual items, the mean number satisfactorily addressed was 7.63 +/- 2.84 (mean +/- S.D.) for 40 papers published from 1955 through 1982, 6.80 +/- 3.86 for 66 papers published from 1983 through 1986, and 11.91 +/- 4.79 for 58 papers published from 1987 through 1990 (F = 31.3, p < .001). We noted that methodology has definitely improved since our first survey of meta-analyses, but an urgent need still exists for a better search of the literature, quality evaluation of trials, and a synthesis of the results. Recently, meta-analysis has expanded to cover non-randomized studies, including evaluation of diagnostic tests and pooling of epidemiologic studies. There is growing concern for standards, and several methodologic issues remain unresolved.

Paternal smoking during pregnancy and the risk of childhood brain tumors: results of a meta-analysis.

OBJECTIVE: Prior epidemiological studies suggest a possible association between paternal smoking during pregnancy and risk of childhood brain tumors (CBT). A meta-analysis was performed statistically pooling all available observational studies on this topic in order to evaluate this suspected association. METHODS: Using previously described methods, a protocol was developed for a meta-analysis examining the association between paternal smoking during pregnancy and subsequent development of primary brain tumors in their offspring. Literature search techniques study inclusion criteria and statistical procedures were prospectively defined. Data from epidemiological studies were pooled using a general variance based meta-analytic method employing confidence intervals previously described by Greenland. The outcome of interest was a summary relative risk (RRs) reflecting the risk of childhood brain tumor development associated with father's smoking during the index pregnancy. Sensitivity analyses were performed when necessary to explain any observed statistical heterogeneity and/or to evaluate the impact of demographic or study characteristics on the summary estimate of effect. RESULTS: Seven observational studies meeting protocol specified inclusion criteria were obtained via a comprehensive literature search. These studies enrolled a total of 3,600 patients. Analysis for homogeneity demonstrated that the data were homogeneous (P = 0.52) and could be statistically combined. Pooling all seven reports yielded a RRs of 1.29 (1.07-1.53), a statistically significant result suggesting a 29% increased risk of brain tumor development associated with paternal smoking during pregnancy. An analysis of father's smoking impact on CBT risk based on "ever" versus "never" smoking history gave a RRs of 1.14 (0.98-1.34), a marginally non-statistically significant result. CONCLUSION: The available epidemiological data suggest an association between paternal smoking during pregnancy and pediatric brain tumor development. Although this association is biologically plausible, limitations in study designs limit definitive conclusions based on available data.

Dietary beta-carotene intake and the risk of epithelial ovarian cancer: a meta-analysis of 3,782 subjects from five observational studies.

OBJECTIVE: The etiology of epithelial ovarian cancer is unknown. Prior work suggests that high dietary beta-carotene intake is associated with a decreased risk of this tumor although this association remains speculative. A meta-analysis was performed to evaluate this suspected relationship. METHODS: Using previously described methods, a protocol was developed for a meta-analysis examining the association between high dietary beta-carotene intake versus low intake and the risk of epithelial ovarian cancer. Literature search techniques, study inclusion criteria and statistical procedures were prospectively defined. Data from observational studies were pooled using a general variance based meta-analytic method employing confidence intervals previously described by Greenland. The outcome of interest was a summary relative risk (RRs) reflecting the risk of ovarian cancer associated with high beta-carotene intake versus low dietary intake. Sensitivity analyses were performed when necessary to evaluate any observed statistical heterogeneity. RESULTS: Five observational studies enrolling 3,782 subjects were initially pooled in a meta-analysis subsequent to an analysis showing a lack of statistical heterogeneity. The meta-analysis showed a summary relative risk of 0.84 with a 95% confidence interval of 0.75-0.94, a statistically significant result. These data suggest that high (versus low) dietary intake of beta-carotene is associated with a sixteen percent decrease in ovarian cancer risk. Sensitivity analyses showed no impact of study design or differences in quantitative measure of beta-carotene intake across studies on the summary relative risk. CONCLUSIONS: High dietary intake of beta-carotene appears to represent a protective factor for the development of ovarian cancer although its magnitude is modest. Further work is needed to clarify factors that may modify the effects of beta-carotene in vivo.

Searching for signals: mortality and cardiovascular events in published randomized control trials of nifedipine in ischemic heart disease and hypertension.

UNLABELLED: META-ANALYSIS: A meta-analysis of published randomized control trials of nifedipine in hypertension and stable angina pectoris was performed. RESULTS: The results suggest a formulation-dependent increased risk of mortality and adverse cardiovascular outcomes for monotherapy use in patients with stable angina pectoris. No increased risk was seen in the hypertension studies.

Improving compliance in depression: a systematic review of narrative reviews.

BACKGROUND AND OBJECTIVE: Narrative reviews represent a popular source of information for clinicians, especially where the evidence on a given subject is sparse and analogies from other fields of medicine may help in filling the information gap. Unfortunately, narrative reviews often follow less stringent criteria for information selection and appraisal than systematic reviews, potentially leading to incomplete or biased recommendations. The objective of the present study was to examine the quality of the recommendations provided by narrative reviews on how to improve patient adherence to pharmacological treatment of unipolar depressive disorders. METHOD: We sought to locate all narrative review papers addressing adherence to treatment in unipolar depressive disorders. In order to do so, we searched Medline and PsychInfo from 1980 to December 2003, using the following keywords: review, depressive disorders, treatment, dropout, patient compliance and adherence. We inspected the title and the abstract, whenever available to identify the relevant reviews and obtained a full copy of the publications in this subset, and read the articles to identify further relevant reviews. These were in turn copied and reviewed, until no further references were found. RESULTS AND DISCUSSION: We identified 23 reviews, providing a total of 87 recommendations. The most common recommendation was for patient education (19 times), patient-physician empathy/alliance (14 times), and education of family (nine times). Reviewers' recommendations were based on the literature on depression 54 times, and on other medical conditions 17 times. A critical appraisal of the evidence base of the recommendations showed that randomized controlled trials or meta-analyses were quoted to support the recommendations only 23% of the times, while important interventions of proven efficacy in the field of depression or in other chronic conditions (e.g. medication clinics, training of nurses, psychological treatment, and telephone follow-up) were not mentioned. CONCLUSIONS: Narrative reviews on adherence to pharmacological treatment of depressive disorders suffer not only from the limited availability of good quality evidence, but also from an incomplete critical appraisal of available evidence on interventions both for depression and for other chronic disorders.