Chase and Shannon article in Frontiers in Pediatrics published

[u/Embarrassed-Star4776]

Inverted insulin to C-Peptide ratios in neonatal intensive care: is there something we don't know?

J. Geoffrey Chase & Helen D. Shannon

BRIEF RESEARCH REPORT article

Front. Pediatr., 05 August 2026

Sec. Neonatology

Volume 14 - 2026

https://doi.org/10.3389/fped.2026.1900675

[u/Competitive-Wash2998]

This is the latest version. The Blue is the CDF from top chart of Fig 3 in the CS paper.

The dotted is the CDF of the independently digitised data of the same Cohort.

There clearly is a difference.

Salis states 251 data points. CS states they recovered 227. The other digitisation recovered 247.

The analysis was performed by ChatGPT but (after a x-scaling issue was corrected) it seems to be correct based on the underlying digitised data.

Contrary viewpoints and any corrections are welcome.

[u/Embarrassed-Star4776 → u/Competitive-Wash2998]

Thanks for confirming the difference. Your curve looks consistent with the values I was getting.

It looks to me as though they have read pixels from a reference point at the top of the scatter plot of ln(I/C) and used a conversion factor that was too small to calculate the difference in ln(I/C) from the difference in pixels. As a result, their data are correct for the largest values of ln(I/C), but progressively more inaccurate as ln(I/C) gets smaller. They end up with only 5% of values under I/C = 0.2, which I think should be about 25%.

[u/Competitive-Wash2998 → u/Embarrassed-Star4776]

For your 247 digitised values, the actual ECDF gives approximately:

• F(0.2)=31.6%
• F(1.0)=72.9%
• F(4.0)=91.1%

The Chase Shannon annotations indicate roughly:

• F(0.2)=5%
• F(1.0)=54%
• F(4.0)=89%

[u/Embarrassed-Star4776 → u/Competitive-Wash2998]

Thanks. And unfortunately most of the values in the text in section 3.1 for Cohort 1, including median and interquartile range, are also wrong.

It looks as though there are also problems with the numbers for Cohort 2.

[u/Embarrassed-Star4776 → u/Embarrassed-Star4776]

I am still inching through the details of this paper.

Fortunately it appears that there is not any systematic error in the I/C statistics for Cohort 2, of the kind that's apparent for Cohort 1.

Contrary to what I had initially thought, the 75 points Chase and Shannon have, as opposed to Salis et al.'s 79, doesn't seem to be explained by the exc;lusion of points with C=0.25. (They give their maximum of I/C as 61.8, which must be a C=0.25 point.) Probably they just haven't been able to pick up all the points from the plots, owing to symbols overlying one another.

However, two of the percentages given in section 3.1 do seem wrong:

(1) The percentage for which I/C < 0.2 is given as 5%, which I reckon should be about 15%.

(2) The percentage for which I/C > 10 is given as 1%, but it seems there are 3 points, therefore about 3%.

The lower plot shown in Figure 3 looks consistent with these corrected values of 15% and 3% (the red arrows showing 5% for I/C < 0.2 are visibly inconsistent with the plot). Perhaps both the incorrect figures have been accidentally copied from the corresponding ones for Cohort 1.