Math gifted help: logistic regression analysis predictive formula for SVR

[Aaron57]

Is anyone gifted enough to interpret and explain in layman's terms this logistic regression analysis predictive formula for SVR ?

This is a interesting 2010 study , unfortunately some of the math involved is above my ability to calculate it.

Full article here : http://www.wjgnet.com/1007-9327/16/89.pdf


Predictive formulae of svr by logistic regression analysis
According to the method of logistic regression analysis,
we derived four formulae to predict SVR of patients
receiving 48-wk PEG-IFN plus RBV treatment in our
cohort from significant factors selected by multivariate
analysis at pretreatment and week 4, week 12 and week
24 as shown in Table 2.

These formulae are as follows:

Pretreatment: 1/p = 1 + exp {-[-8.8065 - 0.0114 ×
RBC (× 104) 0 wk + 0.0812 × PLT (× 104) 0 wk + 1.2552
× log (ALT 0 wk)]}

At week 4: 1/p = 1 + exp [-(-1.8839 - 0.00607 × Age
+ 3.2992 × log (ALT 0 wk) + 1.8784 × RVR - 3.3364 ×
log (AST 4 wk)]

At week 12: 1/p = 1 + exp {-[-11.5278 + 3.672 × log
(ALT 0 wk) + 1.1036 × RVR + 2.1211 × EVR + 0.000837
× WBC 4 wk - 3.0134 × log (AST 12 wk) + 0.418 ×
RBV dose 12 wk]}

At week 24: 1/p = 1 + exp {-[-14.5754 + 4.2296 ×
log (ALT 0 wk) + 1.2028 × RVR + 3.4587 × HCV RNA
24 wk + 0.0009 × WBC 4 wk - 3.3224 × log (AST 12
wk) + 0.4741 × RBV dose 12 wk]}
HCV RNA (-): 1, (+): 0.



Thank you very much , in advance , Aaron

[Aaron57]

Thanks Robert , the symbols  [- {  ,  at the beginning of the equation  mean that 1 + exp - the rest of the equation ?

I didn't want to post much of the study as it's fairly long (wall of text) ...the analysis data :

Multivariate analysis for contributing factors to achieve
SVR

Multivariate analysis was performed to determine the
factors contributing to SVR. Analysis was made pretreatment
and at weeks 4, 12 and 24.

Factors available from
pretreatment until at the time point were all included, and
those calculated as P < 0.1 by univariate analysis at each
time point were analyzed using the logistic regression
method.

A statistical difference was found in gender, age,
RBC, Hb, PLT and log (ALT 0 wk: ALT levels at week 0)
at pretreatment by univariate analysis.

The independent
factor contributing to SVR was RBC (P = 0.024) at pretreatment.

Among significant factors found by univariate
analysis at week 4, log (ALT 0 wk) (P = 0.015),

RVR(4 wk) (P = 0.0049), and log (AST 4 wk) (P = 0.042) were
independent factors by multivariate analysis.

Similarly,
log (ALT 0 wk) (P = 0.0076), EVR (P = 0.0083), WBC
(4 wk) (P = 0.035), and average cumulative RBV dose (P
= 0.045) were significant factors at week 12.

Independent contributing factors at week 24 were :

log (ALT 0 wk) (P =0.0047), HCV RNA (-/+) (24 wk) (P = 0.005),

WBC (4wk) (P = 0.044), log (AST 12 wk) (P = 0.044)

and average cumulative RBV dose (12 wk) (P = 0.040) (Table 2).

It was intriguing in addition to RVR and EVR that baseline ALT
level (log) always affected SVR prediction from pretreatment
until week 24.

Table 2 : Logistic regression analysis of independent predictive
factors for sustained virological response

Variables Odds ratio 95% CI P value

At pretreatment

RBC (× 104) (0 wk) 1.011 1.002-1.021 0.024
PLT (× 103) (0 wk) 1.085 0.986-1.193 0.095
log (ALT 0 wk) 3.509 0.727-16.934 0.118

At week 4
Age 0.941 0.885-1.000 0.051
log (ALT 0 wk) 27.090 1.891-388.001 0.015
RVR +/- 6.543 1.766-24.243 0.0049
log (AST 0 wk) 0.036 0.001-0.886 0.042

At week 12
log (ALT 0 wk) 39.331 2.648-584.144 0.0076
RVR +/- 3.015 0.694-13.100 0.141
EVR +/- 8.340 1.728-40.265 0.0083
WBC (4 wk) 1.001 1.000-1.002 0.035
log (AST 12 wk) 0.049 0.002-1.037 0.053
RBV dose (12 wk) 1.519 1.010-2.284 0.045

At week 24
log (ALT 0 wk) 68.688 3.669 to < 999.999 0.0047
RVR +/- 3.329 0.819-13.529 0.093
EVR +/- 31.775 2.840-355.460 0.0050
WBC (4 wk) 1.001 1.000-1.002 0.044
log (AST 12 wk) 0.036 0.001-0.918 0.044
RBV dose (12 wk) 1.607 1.021-2.528 0.040






FlGuy ,

The PI's won't be an option in many other parts of the world other than U.S. , Canada & Europe after FDA approval  .... for several years ......

Consider the extra Sx , risk of viral mutations & unknown cost of adding another drug to the mix + and maybe most importantly .... unexperienced Tx naive Doctors trying to treat with this new mix .....

Nothing simple about it ....  

Aside from that ..

I'm 16 wks into 1st try SOC , your equation is not at all relevant to my question ....

[FlGuy]

This is a simpler way to look at it

RBV x 6 + A2B x 180 x 48 = RBV x 6 + A2A x 180 + vx950 / 2

[RobertBeWell]

Didn't they summarize their findings?

It seems to me that all you'd have to do is plug in the values for the variables in each formula. There's nothing fancy there, it just looks complicated because of the "wall of text" effect.

You're solving for 1/p, which is the probability if I remember from my college stats days. It will have a value between 0 and 1.

RBW

[James10500]

Hey math I'm not a therapist solve your own problems.

Haha

I've taken stats but, that was another brain ago.