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Santaguida PL, Balion C, Hunt D, et al. Diagnosis, Prognosis, and Treatment of Impaired Glucose Tolerance and Impaired Fasting Glucose. Rockville (MD): Agency for Healthcare Research and Quality (US); 2005 Sep. (Evidence Reports/Technology Assessments, No. 128.)

**This publication is provided for historical reference only and the information may be out of date.**

## Diagnosis, Prognosis, and Treatment of Impaired Glucose Tolerance and Impaired Fasting Glucose.

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**
Section A:
**

**Calculation of kappa coefficient and confidence intervals (CI)**

The simple kappa coefficient is calculated as:

where

andThe Variance and CI are calculated as follows:

where

and

**
Section B:
**

**Calculation of annualized relative risk, annualized risk for the exposed (IFG or IGT) and the normal glucose groups**

Calculation of relative risk (*RR _{ t}*) at time

*t*would be as follows:

where

= Calculated Risk in Exposed Group at time t (or i.e. in Male) and calculated as:

= Calculated Risk in Control Group at time t (or i.e. in Female)

and can be calculated as:

is Observed Risk after T period in Exposed Group

is Observed Risk after T period in Control Group

thus

where

*T*= Observed duration of study (0.5 to 18 years).

*t*= Up to one year study duration.

**
Section C:
**

**Calculation of 95% confidence intervals (CI) for the unadjusted annualized RR**

Where:

**
Section D:
**

**Calculation and test of heterogeneity (Q) and the pooled estimate of RR{36574}:**

Where k is the number of studies being combined, *RR _{ i}* is
the relative risk estimate in i

^{th}Study,

is the weighted estimator of relative risk, and *W _{ i}* is
the weight attached to that study (the reciprocal of the variance of the
i

^{th}study, var

*RR*).

_{ i}
*Q* is approximately distributed as a *X*
^{2} distribution with *k*- 1 degrees of freedom under
*H _{ 0}*

Fixed effects model

Random effect model

and

Further, define

**The estimated component of variance due to inter-study variation in effect
size,, is calculated as:**

and

Adjusted weights for each of the studies is calculated as

**The mean relative risk estimate of all studies can then be computed by:**

**The variance of this estimate is calculated as:**

**U.S. Department of Health and Human Services**

Mike Leavitt,* Secretary*

**Office of Public Health and Science**

Richard H. Carmona, M.D., M.P.H., F.A.C.S.,* Surgeon General of the United
States*

**Agency for Healthcare Research and Quality**

Carolyn M. Clancy, M.D.,* Director*

- Appendix G. Calculations - Diagnosis, Prognosis, and Treatment of Impaired Gluco...Appendix G. Calculations - Diagnosis, Prognosis, and Treatment of Impaired Glucose Tolerance and Impaired Fasting GlucoseBookshelf

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