ABSTRACT
BACKGROUND: Clinicians, providers and guideline panels use absolute effects to weigh the advantages and downsides of treatment alternatives. Relative measures have the potential to mislead readers. However, little is known about the reporting of absolute measures in systematic reviews. The objectives of our study are to determine the proportion of systematic reviews that report absolute measures of effect for the most important outcomes, and ascertain how they are analyzed, reported and interpreted. METHODS/DESIGN: We will conduct a methodological survey of systematic reviews published in 2010. We will conduct a 1:1 stratified random sampling of Cochrane vs. non-Cochrane systematic reviews. We will calculate the proportion of systematic reviews reporting at least one absolute estimate of effect for the most patient-important outcome for the comparison of interest. We will conduct multivariable logistic regression analyses with the reporting of an absolute estimate of effect as the dependent variable and pre-specified study characteristics as the independent variables. For systematic reviews reporting an absolute estimate of effect, we will document the methods used for the analysis, reporting and interpretation of the absolute estimate. DISCUSSION: Our methodological survey will inform current practices regarding reporting of absolute estimates in systematic reviews. Our findings may influence recommendations on reporting, conduct and interpretation of absolute estimates. Our results are likely to be of interest to systematic review authors, funding agencies, clinicians, guideline developers and journal editors.
Subject(s)
Numbers Needed To Treat , Research Design , Research Report/standards , Systematic Reviews as Topic , Data Interpretation, Statistical , Evidence-Based Medicine , HumansABSTRACT
This study evaluates the effect of polymer molecular weight and charge density, algogenic organic matter (AOM), and salt concentration on harvesting efficiency of marine microalgae. Aluminum chloride (AlCl3), chitosan, and five synthetic cationic polymers of different molecular weights and charge density levels were used as flocculation agents. Polymer flocculation of marine microalgae was most efficient when using the highest charge density polymer (FO4990). The flocculant dosage irrespectively of the agent chemistry and charge density was affected by the amount of AOM secreted into the culture media. The presence of AOM increased the amount of required flocculant 7-fold when using synthetic cationic polymers; 10-fold with chitosan; and ~3-fold with AlCl3. Salt concentration of 5 or 35 g/L NaCl alone did not significantly affect removal efficiency, indicating that AOM were the main cause for the increased flocculant dosage requirement. The synthetic cationic polymer (FO4990) was the least expensive flocculation agent.
Subject(s)
Flocculation , Organic Chemicals/chemistry , Sodium Chloride/chemistry , Stramenopiles/metabolism , Biomass , Marine Biology , Stramenopiles/growth & developmentABSTRACT
Process variables affecting harvesting efficiency of Nannochloris oculata by AlCl(3) flocculation such as, cell density, ionic strength, coagulant dosage, media pH, and cell surface charge were investigated. Initial cell density and coagulant dosage had a significant effect on the removal efficiency; however, levels of ionic strength tested were not significant. Best flocculation conditions of investigated variables were: 0.0016 ng of AlCl(3)/cell, 3.0×10(7) cell/mL, and pH 5.3. Removal efficiency at optimum conditions and salt concentrations of: 0, 15, and 30 g/L NaCl was 96, 98, and 97 %, respectively. Low cell density cultures â¼10(6) cell/mL, required five times greater AlCl(3) dosage to achieve the same removal efficiency. Destabilization of algal cultures using 0.0032 ng of AlCl(3)/cell was observed by reducing the zeta potential to -22 mV. Acidification with HCl for conducting flocculation at pH 5.3 could be a significant cost burden unless is mitigated by selecting a low-buffering-capacity media.
