Intracluster correlation coefficients for sample size calculations related to cardiovascular disease prevention and management in primary care practices

Table 3 ICC estimates for clinical outcomes

Clinical Outcome	N	Average cluster size	Mean	Standard Deviation	ICC
All patients
SBP	4771	57	130.8	16.6	0.054
DBP	4771	57	75.5	10.1	0.094
LDL	3805	45	2.43	0.93	0.035
HDL	3355	40	3.39	0.78	0.020
FBG	4053	48	6.64	2.2	0.023
eGFR	4000	48	72	18.6	0.015
ACR	1589	19	9.4	43.6	0.000*
Patients with Hypertension
SBP	3746	45	132.6	16.6	0.055
DBP	3746	45	76.1	10.2	0.091
Patients with Dyslipidemia
LDL	3395	40	2.39	0.94	0.033
HDL	2997	36	3.38	0.77	0.019
Patients with Diabetes
SBP	2226	27	130.9	16.4	0.038
LDL	1856	22	2.23	0.9	0.054
HDL	1663	20	3.38	0.8	0.039
HbA1c	1999	24	0.074	0.0	0.003
FBG	1986	24	7.83	2.6	0.022
eGFR	1963	23	73.9	19.7	0.016
ACR	1199	14	10.23	44.0	0.000*
Patients with Chronic Kidney Disease
eGFR	859	10	51.5	16.79	0.058
SBP	922	11	130	18.02	0.078
DBP	921	11	72.8	10.73	0.115
Patients with Coronary Artery Disease
SBP	1452	17	128.2	17.75	0.069
DBP	1453	17	72.9	10.12	0.124
LDL	1136	14	2.13	0.78	0.053
HDL	1049	12	3.29	0.75	0.006
Patients who Smoke
SBP	995	12	130.4	17.3	0.013
DBP	994	12	76.7	10.1	0.070
LDL	757	9	2.58	1.0	0.026
HDL	611	7	3.55	0.8	0.018

SBP – Systolic Blood Pressure, DBP – Diastolic Blood Pressure, LDL – Low Density Lipoprotein, HDL – High Density Lipoprotein, FBG – Fasting Blood Glucose, eGFR – Estimated Glomerular Filtration Rate, ACR – Albumin-to-Creatinine ratio, HbA1c – Hemoglobin A1c; *Negative ICCs were considered a result of sampling error and were set to zero.

ISSN: 1756-0500