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Ryan
Ryan, Engineer
Category: Calculus and Above
Satisfied Customers: 8912
Experience:  B.S. in Civil Engineering
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Aim: To evaluate the Impact of switching from Lucentis to

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Aim: To evaluate the Impact of switching from Lucentis to Eylea in nAMD patients inadequately responding to Lucentis.Twenty eyes of 17 patients were identified for inclusion in this study.All patients were previously treated with Lucentis for one year
(Visual acuities (VA) are recorded as ETDRS letter scores)Initial visual acuity (VA), (prior to treatment with Lucentis): Mean = 64.75 (SD 12.53994), range : 46- 85
VA at one year after treatment with Lucentis: Mean 58.85 ( SD 13.35458 ), range: 31- 83
Gain/loss of VA at one year of treatment with Lucentis: -5.9 (SD 7.2830011), range: -20 to +4The cohort of patients was then treated with Eylea for one year. (switched to Eylea from Lucentis)VA at switch: Mean 58.85 (SD 13.35458), range 31-83
VA at six months post switch: Mean 63.85 (SD 15.38377) range: 46-94
Gain/loss of VA at six months post switch: +5.0 (8.169262) range: -7 to +23VA at one year post switch: Mean 60.0 (SD 16.48) range: 31- 92
Gain/loss of VA at one year post switch: +1.15 (SD 9.143735273) , range: -13 to +23Results:
It appears that the drug Eylea improved Mean VA at 6 months and also at one year after the switch.
Question:
Is this improvement if mean VA statistically significant, at six months and at one year?
Submitted: 10 months ago.
Category: Calculus and Above
Expert:  Ryan replied 10 months ago.
Hi, Thank you for using the site. I'll be happy to help you with this problem. I'll have a solution posted for you soon. Thanks, Ryan
Expert:  Ryan replied 10 months ago.
Hi again, Here are the hypothesis tests and conclusions: HypothesisTests Please feel free to ask if you have any questions about the results. Thanks, Ryan
Customer: replied 10 months ago.
You have not answered my question:
The 'Hypothesis tests' led me to a website to download their product.
The question is about the statistical significance of the outcomes. If you have worked this out, please send me your conclusions. If you are not familiar with statistics, please let let me know. Please do not waste my time. Thank you.
Expert:  Ryan replied 10 months ago.
Hello, I'm sorry to hear that the link that was posted did not work for you as intended. The intent was to provide a way that you could download the solution to your question as a Word document, and you should not have been asked to download any "product". I have attached the Word document to this reply, so you should be able to access the file without using any other websites. Please let me know if you have any difficulty obtaining the file. The short answer to your question is that the change in visual acuity is statistically significant after 6 months of treatment, but not after 1 year. The supporting work for these conclusions is contained in the Word document. Please feel free to ask if you have any additional questions regarding this solution. Thanks, Ryan
Customer: replied 10 months ago.
Hi Ryan, Thanks for the analysis.
This is the outcomes of the same cohort of patients treated for one year with Lucentis and then for one year with Eylea. Would you be able to analyze this as paired data? If further data is required, Please let me know.
Many thanks.
Expert:  Ryan replied 10 months ago.
To analyze it as paired data, we would need the before and after visual acuity values for each eye that was measured.In other words, for each patient, we would need their beginning VA when they started with Eylea, their VA at 6 months, and their VA at 1 year. If that data was available, then we could test the mean of the differences measured for each patient/eye. This would be different than taking the average of the visual acuity values for each case, and then taking the difference of those averages, as was done in the solution that I sent to you. The conclusions might turn out to be the same either way, but the supporting evidence will likely turn out to be different. As for the solution that was posted, the fact that the patients were treated with Lucentis in the previous year is of little interest as far as the research question is concerned. It sets a condition on the conclusions, such that the results may only be valid for future patients who are treated with Lucentis first, and then switched to Eylea. Patients who are treated with ONLY Eylea could see different results, which could be better or worse. It also establishes that all of the patients are starting the study with something of the same baseline regarding their visual acuity status. But the focus of the research question is whether Eylea improved the patient's VA after 6 months of treatment, and after 1 year of treatment.
Customer: replied 10 months ago.
Hi Ryan,
I have given below the values (initial= before any treatment, 'At switch' is when the drug Lucentis was switched to Eylea at one year, and then the VA at 6 and 12 months later. I would very much appreciate it if paired data analysis could be done.
Many thanks.initial VA At Switch at 6M at1year
GC 64 54 48 48
VE 62 64 63 66
SH 50 50 53 50
AK 48 31 46 31
MM 64 60 63 47
MM 57 49 57 52
IP 82 69 69 69
AT 46 46 49 46
AT 60 47 49 47
SW 60 60 83 83
SW 61 61 77 77
SW 47 49 50 57
PA 80 60 75 47
HC 84 76 89 84
GM 79 83 78 75
GM 75 75 75 69
VB 58 48 48 46
FI 70 53 46 46
RS 85 83 94 92
SN 63 59 65 68
Mean 64.75 58.85 63.85 60
SD 12.53994 13.35458 15.38377 16.48
Expert:  Ryan replied 10 months ago.
Ok, no problem. I'll get this back to you as quickly as I can. Ryan
Expert:  Ryan replied 10 months ago.
It turns out that the statistics that were included in your original post are, in fact, from paired data. In particular, the mean and standard deviations given in the following two lines Gain/loss of VA at six months post switch: +5.0 (8.169262) range: -7 to +23Gain/loss of VA at one year post switch: +1.15 (SD 9.143735273) , range: -13 to +23 actually do come from the paired data. It just wasn't possible to see that definitively without the raw data. Please let me know if there is anything else that I can do to help. Thanks, Ryan
Ryan, Engineer
Satisfied Customers: 8912
Experience: B.S. in Civil Engineering
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Customer: replied 10 months ago.
Thank you very much
Expert:  Ryan replied 10 months ago.
You are quite welcome. I'm glad that I could help. Regards, Ryan

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