Bioequivalence and Bioavailability Forum • Calculation of ISR deviation

Calculation of ISR deviation [Bioanalytics]

posted by Helmut – Vienna, Austria, 2013-04-24 16:07 (4809 d 16:37 ago) – Posting: # 10489
Views: 9,108

Dear Ohlbe!

❝ My understanding is what is described in the Crystal City white papers:

❝

❝ (C₁-C₂)/((C₁+C₂)/2).

OK, that’s what we have done in the past. Which CCIII WP are you referring to? I can’t find anything in the Conference Report. Do you mean

Rocci ML, Devanarayan V, Haughey DB, and P Jardieu
Confirmatory Reanalysis of Incurred Bioanalytical Samples
AAPS J 9(3) Article 40 (2007)
online

which states in footnotes

Difference = (Repeat–original)/average expressed as a percentage

BTW, nice examples for the number of ISRs (astonishingly small).

What makes me wonder is that I had to use the ratio of the first to the second measurements in order to reproduce their results.

# Rocci et al. Example 1

first   <- c(478,107,826,108,248,696,141,194,548,676,

             636,635,244,527,139,107,664,187,690,187)

second  <- c(406,107,718,109,250,674,135,179,564,598,

             676,624,240,579,117,99.3,583,176,610,190)

Pct.diff<- 100*(second-first)/((first+second)/2)

Pos.d   <- length(Pct.diff[Pct.diff>0])

Zero.d  <- length(Pct.diff[Pct.diff==0])

Neg.d   <- length(Pct.diff[Pct.diff<0])

diff.r  <- log10(first) - log10(second)  # Step 1

Ratio   <- 10^(diff.r)

mean    <- mean(diff.r)

sd      <- sd(diff.r)

n       <- length(diff.r)

geo.mean<- sqrt(first*second)            # Step 2

MR      <- 10^(mean)                     # Step 3

sig     <- c(-1, +1)

RL      <- 10^(mean+sig*2*sd/sqrt(n))

LA      <- 10^(mean+sig*sd)              # Step 4

Comp    <- length(Ratio[Ratio>=LA[1] & Ratio<=LA[2]])

Comp.pct<- 100*Comp/n

plot(geo.mean, Ratio, las=1, log="xy", pch=16)

abline(h=MR, lwd=2, col="blue")

abline(h=RL, lwd=2, col="darkgreen")

abline(h=LA, lwd=2, col="red")

cat(" MR:", round(MR,2), "\n", "RL:", round(RL,2), "\n",

  "LA:", round(LA,2), "\n", "Ratios with LA:", Comp.pct, "%\n")

Edit: A more comprehensive code over there.

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Complete thread:

Calculation of ISR deviation Helmut 2013-04-23 19:30
- Calculation of ISR deviation ElMaestro 2013-04-23 20:30
  - I see… Helmut 2013-04-23 22:08
  - Calculation of ISR deviation Roberto 2013-12-09 12:52
- Calculation of ISR deviation Ohlbe 2013-04-24 09:40
  - Calculation of ISR deviationHelmut 2013-04-24 14:07
    - Calculation of ISR deviation Ohlbe 2013-04-24 22:37
      - Calculation of ISR deviation Helmut 2013-04-25 02:00