The effectiveness and cost-effectiveness of telephone triage of patients requesting same day consultations in general practice: study protocol for a cluster randomised controlled trial comparing nurse-led and GP-led management systems (ESTEEM)

Table 1 Sample size calculation

Number per group*	ICC	Design factor	Number of patients per group	Final number of patients per group+	Number of practices per group
305*	0.01	3.26	994	1,867	4
305*	0.05	12.3	3,751	7,046	14
228^	0.01	3.26	743	1,396	3
228^	0.05	12.3	2,804	5,267	10

*At 90% power and 5% alpha; ^80% power and 5% alpha (both using the above means and SDs as per text); +after 6%[3, 27, 28] of patients being excluded, 10%[14, 28, 29] initially declining participation, 30%[27–29] non-response to the request to return written consent to note review; of responders, 10% decline note review.

ISSN: 1745-6215