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Table 6 Estimates of the within-period and inter-period correlation for included patients from THIN database from two consecutive periods

From: Intra-cluster and inter-period correlation coefficients for cross-sectional cluster randomised controlled trials for type-2 diabetes in UK primary care

 

Unadjusted model

Adjusted model

Outcome

WPC

IPC

CA

WPC

IPC

CA

 

(SE)

(SE)

 

(SE)

(SE)

 

HbA1ca (%)

0.035

0.019

0.546

0.035

0.019

0.539

(0.003)

(0.003)

 

(0.003)

(0.003)

 

Systolic blood pressureb (mmHg)

0.032

0.021

0.649

0.030

0.019

0.632

(0.003)

(0.003)

 

(0.002)

(0.003)

 

Diastolic blood pressureb (mmHg)

0.040

0.028

0.692

0.040

0.026

0.662

(0.003)

(0.004)

 

(0.003)

(0.004)

 

BMIb (kg/m2)

0.021

0.013

0.612

0.022

0.016

0.747

(0.002)

(0.002)

 

(0.002)

(0.002)

 

Total cholesterolb (mmol/L)

0.021

0.010

0.486

0.021

0.006

0.281

(0.002)

(0.002)

 

(0.002)

(0.002)

 

HDL cholesterolb (mmol/L)

0.021

0.018

0.876

0.020

0.017

0.889

(0.002)

(0.002)

 

(0.002)

(0.002)

 
  1. BMI body mass index, CA cluster autocorrelation, HbA1c glycosylated haemoglobin, HDL high-density lipoprotein, IPC inter-period correlation, SE standard error, WPC within-period correlation. aTwo consecutive 12-month periods were used. bTwo consecutive 15-month periods were used