Table 2.

Changes in prescribing in the UK and self-poisoning in three centres in England in 12–19-year-olds, 2000–2006, associated with the Medicines and Healthcare products Regulatory Authority (MHRA) warning in December 2003

	Estimation of the absolute effect during 2004–2006 of the MHRA warning*
	Mean quarterly estimated number with the MHRA warning†	Mean quarterly estimated number without the MHRA warning†	Conservative mean quarterly estimated number without the MHRA warning†	Mean quarterly change during 2004–2006‡ (95% CIs)¶	Conservative mean quarterly change during 2004–2006§(95% CIs)¶
Prescription rate (per 100 000)
SSRIs**	508.925	1203.893	1033.156	−695 (−602, −788)	−524 (−461, −588)
Fluoxetine	509.920	739.366	634.854	−230 (−125, −334)	−125 (−56, −193)
Tricyclics	296.283	431.473	407.056	−135 (−18, −252)	−111 (−38, −183)
Percent of all self-poisoning episodes using specific drugs
SSRIs**	5.2	9.7	9.2	−4.5 (−1.5, −7.5)	−4.0 (−1.9, −6.1)
Fluoxetine	6.4	4.9	NA	1.5 (−1.2, 4.2)	NA
Tricyclics	2.4	1.6	NA	0.8 (−1.1, 2.6)	NA
Percent of all self-harm episodes using self-poisoning
All drugs and other substances	83.3	83.0	NA	0.3 (−3.9, 4.5)	NA

^*Using Interrupted Time Series Segmented Regression Analysis [21].

^†Medicines & Healthcare products Regulatory Authority (MHRA) warning in December 2003 not to prescribe SSRI antidepressants except fluoxetine to under-18-year-olds.

^‡Difference between column 2 and column 3. See Appendix B for calculation, method ‘a’ using Equation A4.

^§Difference between column 2 and column 4. See Appendix B for calculation, method ‘b’ using Equation A6.

^¶95% Confidence intervals (CI) calculated according to Zhang et al. [28].

^**SSRIs except fluoxetine. NA, not applicable where trend is decreasing in pre-warning period.