Table 2.

Medication possession ratio and persistence of statin users¹ prior to and following breast cancer diagnosis and treatment

Observation period		N	MPR2			MPR2 ≥ 0.8		Discontinuation episodes3				1 - DR4
			Mean	SD	IQR	n	(%)	Mean	Median	SD	IQR	n	(%)
Diagnosis − 1 year	Year −1	1,393	0.778	(0.294)	0.657–0.986	934	67.0%	1.003	1	(1.154)	0–2	704	50.5%
Diagnosis + last treatment	Treatment period5	1,384	0.678	(0.336)	0.500–0.979	718	51.9%	0.490	0	(0.604)	0–1	799	57.7%
Last treatment + 1 year	Year +1	1,129	0.650	(0.346)	0.247–0.986	557	49.3%	1.219	1	(1.250)	0–2	469	41.5%
End of year 1 + 1 year	Year +2	1,040	0.634	(0.296)	0.247–0.986	368	35.4%	1.200	1	(1.159)	0–2	414	39.8%
End of year 2 + 1 year	Year +3	959	0.686	(0.318)	0.329–0.986	482	50.2%	1.176	1	(1.192)	0–2	394	41.1%

¹≥1 Dispensing of statin medication in the year prior to breast cancer diagnosis

²Medication possession ratio (MPR): proportion of days’ supply medication dispensed over the observed days of intended use; patients considered adherent at MPR ≥ 0.8, non-adherent at MPR < 0.8

³Discontinuation episodes: gaps of ≥90 days between dispensing of subsequent filling

⁴Discontinuation rate (DR): proportion of users with at least one discontinuation episode; 1 - DR = proportion of users with no interruptions in therapy

⁵Treatment period: SEER diagnosis date to the latest of primary cancer treatment (surgery, radiation, or chemotherapy) plus 90 days

⁶Mean MPR from all periods are statistically different (P < 0.05) in comparison to Year-1

Abbreviations: SD Standard deviation; IQR Interquartile range