Pretreatment thrombocytosis as a significant prognostic factor in malignant mesothelioma: a meta-analysis

Our plain-English summary of Pretreatment thrombocytosis as a significant prognostic factor in malignant mesothelioma: a meta-analysis, by Y. Zhuo, L. Lin, M. Zhang (Platelets, 2017).

The study

• Authors: Y. Zhuo, L. Lin, M. Zhang
• Journal: Platelets
• Published: 2017;28(6):560-566
• Type of article: Meta-analysis, Review
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The current meta-analysis analyzed the prognostic impact of elevated platelet count before the treatment of malignant mesothelioma (MM). We performed a search for articles published up to April 15, 2016 in PubMed, MEDLINE, EMBASE, and Web of Science, which evaluated elevated platelet count and survival outcome of MM. STATA version 12 was used for statistical analysis. The pooled hazard ratios (HRs) and their 95% confidence intervals (CIs) were combined to calculate overall effects. The assessment of heterogeneity was tested by the Cochran Q and I2 statistics. The sensitivity and meta-regression analyses were performed to explore the origin of heterogeneity. We analyzed 18 eligible studies (3602 patients) that evaluated the correlation between pretreatment platelet count and overall survival (OS). Elevated platelet count was a prognostic factor of poor OS, with a pooled HR of 1.56 (95% CI = 1.36-1.77). However, significant heterogeneity was observed in the included studies (I2 = 86.0%, p < 0.001). Sensitivity and meta-regression analyses were performed to trace the origin of heterogeneity. Only the variable type (multivariable or univariate model) was traced as the origin of heterogeneity. Hence, we conducted a subgroup analysis of variable type. The HR was 1.66 (95% CI = 1.41-1.91) in the multivariable group and no significant heterogeneity was observed (I2 = 0.0%, p = 0.476). In conclusion, high pretreatment platelet count resulted in poor OS in MM. Therefore, platelet count could be an adequate and useful factor of prognosis for MM.

In plain English

This article was a meta-analysis, which pooled the results of earlier published studies. It did not study asbestos exposure. It asked whether a high platelet count (a routine blood test) measured before treatment was linked to shorter survival in people with malignant mesothelioma. The authors searched four databases for studies published up to April 15, 2016. They included 18 studies covering 3602 patients, published from 1995 to 2016. Across all studies, a high platelet count was associated with poorer overall survival (pooled hazard ratio 1.56, 95% CI 1.36–1.77), but results varied widely between studies. In the 12 studies that adjusted for other factors, the hazard ratio was 1.66 (95% CI 1.41–1.91), with no significant variation between studies. In the 6 unadjusted studies, the association was not statistically significant (1.16, 95% CI 0.89–1.42). The authors concluded that a high platelet count is correlated with worse survival and could be a useful prognostic factor. Limitations they noted included differing platelet cutoffs, a long time span with changing treatments, exclusion of non-English articles, and reliance on non-randomized studies.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Systematic review and meta-analysis of published observational (mostly retrospective) studies
• Who was studied: 18 published studies with a total of 3602 patients with malignant mesothelioma (mostly pleural, some peritoneal or mixed sites), published 1995 to 2016, identified in searches up to April 15, 2016
• Exposure: Elevated platelet count (thrombocytosis) measured before treatment. Cutoffs in the included studies ranged from 300 to 450 (×10^3/mm3), most often 400. Asbestos exposure was not examined.
• Main results:
  • Across all 18 studies, elevated platelet count was associated with poorer overall survival: pooled HR 1.56 (95% CI 1.36–1.77)
  • There was significant heterogeneity among the 18 studies (I2 = 86.0%, p less than 0.001)
  • Leaving out any single study did not significantly change the pooled result
  • In the multivariable group (12 studies, 2889 patients), HR 1.66 (95% CI 1.41–1.91), with no significant heterogeneity (I2 = 0.0%, p = 0.476)
  • In the univariate group (6 studies, 713 patients), there was no significant association: HR 1.16 (95% CI 0.89–1.42), with significant heterogeneity (I2 = 89.4%)
  • No significant publication bias was found (Egger's test p = 0.982)
• The authors' conclusion: The authors concluded that thrombocytosis is correlated with worse overall survival in malignant mesothelioma, and that pretreatment platelet count could be an adequate and useful prognostic factor. They said the mechanism and antiplatelet therapy need further investigation.
• Limitations the authors state:
  • Heterogeneity was high, nearly 90% in the univariate group
  • There is no agreed platelet count cutoff value
  • The included studies spanned 1995 to 2016, so treatment protocols may have differed
  • Non-English articles were excluded
  • The included studies were less reliable than prospective randomized trials

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Meta-Analysis, Hazard Ratio, confidence interval, Overall Survival, Prognosis.

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