GetData Graph Digitizer is a program for digitizing graphs and plots. It is often necessary to obtain original (x,y) data from graphs, e.g. from scanned scientific plots, when data values are not available. GetData Graph Digitizer allows to easily get the numbers in such cases.
A systematic literature search was conducted March 2017 to identify data on efficacy and safety outcomes of treatments for frontline CLL. PFS and OS Kaplan-Meier curves were manually digitised using GetData Graph Digitizer (version 2.26). Potential treatment modifying variables were also extracted. Seventeen publications included data for PFS at 24 months (PFS24) and OS at 36 (OS36) and 60 months (OS60). Each treatment arm of each trial was considered as an independent observation. Pearson's correlation was used to calculate the correlation between OS36 or OS60, and treatment modifying variables and PFS24. Significantly correlated variables were then utilised in the robust ordinary least squares (OLS) regression analyses to develop models that could predict OS from PFS. Using the same data, a second analysis was performed with Cox semi-parametric models. First patient-level OS and PFS data were recreated using the Guyot algorithm. Next, to inform the modelling strategy, the validity of proportional hazards (PH) assumptions were checked using three methods: log log plot graphical observation, Cox model check, and Schoenfeld's residuals from the Cox model. Hazard ratios (HRs) were then derived from the models.
Two reviewers will independently perform data extraction and records of study information. The following data will be extracted: name of the first author, publication year, study population (strain, number, sex, age, and weight), model characteristics (method of model, injury level), intervention details (dosage, administration route, timing, and times), and measurements. Moreover, the proposed mechanisms and changes of related molecules will be also extracted from included studies for investigating the neuroprotective mechanism behind edaravone [26, 31]. In studies involving multiple intervention groups, only data from edaravone and negative control groups will be extracted for analyses. If study data are not represented by numerical values but in graphs, we will use the GetData Graph Digitizer 2.26 ( -graph-digitizer.com) to extract the corresponding statistics from the graphs. If the needed data are missing, we will initiate contact with the authors and await a response for a two-week response period. Within waiting period, the original authors will be contacted weekly. If there is no response, the related study will be included for qualitative analyses only, but not be considered for quantitative analyses.
b73f46f91f