Citations alone were enough to predict favorable conclusions in reviews of neuraminidase inhibitors

Association Between Conflicts of Interest and Authors' Positions on Harms of Varenicline: a Cross-Sectional Analysis

BACKGROUND

Few studies have investigated the relationship between industry funding/conflicts of interest and authors' positions in opinion pieces on drug safety. Harmful effects of varenicline, a treatment for smoking cessation, have been highly contested.

OBJECTIVE

To examine the association between pharmaceutical industry funding/authors' financial conflicts of interest and position on varenicline in opinion articles, especially in relation to the minimization of harms; to assess whether opinion pieces on drug safety issues written by authors with conflicts of interest are more frequently cited in the news or social media.

DESIGN

Cross-sectional analysis.

PARTICIPANTS

English language opinion pieces and narrative reviews about varenicline published between May 2006 and February 2019.

MAIN MEASURES

Odds ratios and 95% confidence intervals; the Mann-Whitney two-sample statistic was used to test for differences in Altmetric scores, a measure of media attention.

KEY RESULTS

Of the 221 included articles, 30.3% (67) disclosed the funding source and 62.9% (139) disclosed authors' conflicts of interest. Authors of opinion pieces on varenicline who reported financial ties to the pharmaceutical industry (as a conflict of interest or funding source) were more likely to minimise the cardiovascular and psychiatric risk of varenicline compared to those without conflicts of interest or industry funding (OR: 4.00; 95% CI: 1.32 to 12.16 for cardiovascular risk; OR: 8.51; 95% CI: 3.79 to 19.11 for psychiatric risk). These associations persisted in sensitivity analyses. No statistically significant difference in Altmetric score was found between articles with (mean 15.83, median 3) and without (mean 11.90, median 1) conflicts of interest, indicating similar media attention (p-value=0.11).

CONCLUSIONS

We found that authors with financial ties to drug companies were more likely to publish opinion pieces that minimised harms of varenicline. These results raise questions about journals' editorial policies to accept reviews of treatments from authors with financial relationships with manufacturers.

The timing and frequency of trial inclusion in systematic reviews of type 2 diabetes drugs was associated with trial characteristics

OBJECTIVE

To determine whether certain trial characteristics are associated with faster or more frequent inclusion in systematic reviews for drug interventions in type 2 diabetes.

STUDY DESIGN AND SETTING

We examined trials included in systematic reviews published between January 1, 2007 and January 1, 2017. Primary outcomes were time between trial publication and first inclusion in a systematic review and frequency of inclusion in systematic reviews over the study period. Multivariable Cox proportional hazards and regression models quantified associations with funding source, number of participants, trial conclusion, and journal impact factor.

RESULTS

Among 668 trials, the median time to inclusion was 76.1 weeks. Time to inclusion was shorter for trials with industry funding (hazard ratio [HR] 1.39; 95% confidence interval [CI] 1.13-1.71), more participants (HR 1.26; 95% CI 1.17-1.36), and published in higher impact factor journals (HR 1.28; 95% CI 1.14-1.45). The median frequency of inclusion was three. Frequency of inclusion was greater for trials with industry funding (relative risk [RR] 2.36; 95% CI 2.11-2.64), more participants (RR 1.51; 95% CI 1.47-1.55), positive conclusions (RR 1.89; 95% CI 1.68-2.13), and published in higher impact factor journals (RR 1.13; 95% CI 1.08-1.18).

CONCLUSION

Certain trial characteristics are associated with faster or more frequent trial inclusion in systematic reviews of type 2 diabetes.

Selective citation in the literature on swimming in chlorinated water and childhood asthma: a network analysis

Background

Knowledge development depends on an unbiased representation of the available evidence. Selective citation may distort this representation. Recently, some controversy emerged regarding the possible impact of swimming on childhood asthma, raising the question about the role of selective citation in this field. Our objective was to assess the occurrence and determinants of selective citation in scientific publications on the relationship between swimming in chlorinated pools and childhood asthma.

Methods

We identified scientific journal articles on this relationship via a systematic literature search. The following factors were taken into account: study outcome (authors' conclusion, data-based conclusion), other content-related article characteristics (article type, sample size, research quality, specificity), content-unrelated article characteristics (language, publication title, funding source, number of authors, number of affiliations, number of references, journal impact factor), author characteristics (gender, country, affiliation), and citation characteristics (time to citation, authority, self-citation). To assess the impact of these factors on citation, we performed a series of univariate and adjusted random-effects logistic regressions, with potential citation path as unit of analysis.

Results

Thirty-six articles were identified in this network, consisting of 570 potential citation paths of which 191 (34%) were realized. There was strong evidence that articles with at least one author in common, cited each other more often than articles that had no common authors (odds ratio (OR) 5.2, 95% confidence interval (CI) 3.1-8.8). Similarly, the chance of being cited was higher for articles that were empirical rather than narrative (OR 4.2, CI 2.6-6.7), that reported a large sample size (OR 5.8, CI 2.9-11.6), and that were written by authors with a high authority within the network (OR 4.1, CI 2.1-8.0). Further, there was some evidence for citation bias: articles that confirmed the relation between swimming and asthma were cited more often (OR 1.8, CI 1.1-2.9), but this finding was not robust.

Conclusions

There is clear evidence of selective citation in this research field, but the evidence for citation bias is not very strong.

Survival biases lead to flawed conclusions in observational treatment studies of influenza patients

BACKGROUND AND OBJECTIVE

Several observational studies reported that Oseltamivir (Tamiflu) reduced mortality in infected and hospitalized patients. Because of the restriction of observation to hospital stay and time-dependent treatment assignment, such findings were prone to common types of survival bias (length, time-dependent and competing risk bias).

METHODS

British hospital data from the Influenza Clinical Information Network (FLU-CIN) study group were used which included 1,391 patients with confirmed pandemic influenza A/H1N1 2009 infection. We used a multistate model approach with following states: hospital admission, Oseltamivir treatment, discharge, and death. Time origin is influenza onset. We displayed individual data, risk sets, hazards, and probabilities from multistate models to study the impact of these three common survival biases.

RESULTS

The correct hazard ratio of Oseltamivir for death was 1.03 (95% confidence interval [CI]: 0.64-1.66) and for discharge 1.89 (95% CI: 1.65-2.16). Length bias increased both hazard ratios (HRs): HR (death) = 1.82 (95% CI: 1.12-2.98) and HR (discharge) = 4.44 (95% CI: 3.90-5.05), whereas the time-dependent bias reduced them: HR (death) = 0.62 (95% CI: 0.39-1.00) and HR (discharge) = 0.85 (95% CI: 0.75-0.97). Length and time-dependent bias were less pronounced in terms of probabilities. Ignoring discharge as a competing event for hospital death led to a remarkable overestimation of hospital mortality and failed to detect the reducing effect of Oseltamivir on hospital stay.

CONCLUSIONS

The impact of each of the three survival biases was remarkable, and it can make neuraminidase inhibitors appear more effective or even harmful. Incorrect and misclassified risk sets were the primary sources of biased hazard rates.

Why do we think we know what we know? A metaknowledge analysis of the salt controversy

BACKGROUND

Although several public health organizations have recommended population-wide reduction in salt intake, the evidence on the population benefits remains unclear. We conducted a metaknowledge analysis of the literature on salt intake and health outcomes.

METHODS

We identified reports--primary studies, systematic reviews, guidelines and comments, letters or reviews--addressing the effect of sodium intake on cerebro-cardiovascular disease or mortality. We classified reports as supportive or contradictory of the hypothesis that salt reduction leads to population benefits, and constructed a network of citations connecting these reports. We tested for citation bias using an exponential random graph model. We also assessed the inclusion of primary studies in systematic reviews on the topic.

RESULTS

We identified 269 reports (25% primary studies, 5% systematic reviews, 4% guidelines and 66% comments, letters, or reviews) from between 1978 and 2014. Of these, 54% were supportive of the hypothesis, 33% were contradictory and 13% were inconclusive. Reports were 1.51 [95% confidence interval (CI) 1.38 to 1.65] times more likely to cite reports that drew a similar conclusion, than to cite reports drawing a different conclusion. In all, 48 primary studies were selected for inclusion across 10 systematic reviews. If any given primary study was selected by a review, the probability that a further review would also have selected it was 27.0% (95% CI 20.3% to 33.7%).

CONCLUSIONS

We documented a strong polarization of scientific reports on the link between sodium intake and health outcomes, and a pattern of uncertainty in systematic reviews about what should count as evidence.