Impact of statin therapy on postoperative outcomes following colorectal cancer surgery: A systematic review

Table 1 Quality assessment

Dimension	Selection
Ref.	Representative of the exposed cohort	Selection of the nonexposed control	Ascertainment of exposure	Outcome of interest not present at the start of the study
Löffler et al[16]	1	1	1	1
Bahl et al[15]	1	1	1	1
Pourlotfi et al[9]	1	1	1	1
Disbrow et al[10]	1	1	1	1
Fransgaard et al[11]	1	1	1	1
	Comparability; comparability of cohorts; control of important and additional factors
Löffler et al[16]	2
Bahl et al[15]	1
Pourlotfi et al[9]	1
Disbrow et al[10]	1
Fransgaard et al[11]	1
Ref.	Assessments of outcomes	Sufficient follow up time for outcomes to occur	Adequacy of follow-up of cohorts
Löffler et al[16]	1	1	0
Bahl et al[15]	1	1	0
Pourlotfi et al[9]	1	1	1
Disbrow et al[10]	1	1	1
Fransgaard et al[11]	1	1	1
Ref.	Total
Löffler et al[16]	8
Bahl et al[15]	7
Pourlotfi et al[9]	8
Disbrow et al[10]	8
Fransgaard et al[11]	8

Table 2 Comparative overview of the outcome: Anastomotic leakage

	Disbrow et al[10]	Fransgaard et al[11]	Bahl et al[15]
Statin therapy definition	No information available concerning statin medication choice, dose, and duration of use	Statin user is defined as redeeming 2 or more statin prescriptions 1 year before surgery; postoperative continuation period not stated	Short-term statin therapy group: Preoperative statin use (3-7 days) and postoperative duration (14 days); long-term statin therapy group: Ongoing statin therapy
Type of surgical data	Colectomy and rectal resection combined and separate	Combined colorectal	Combined colorectal
Comorbidities	Diabetes; COPD; ascites/cirrhosis; hypertension; congestive heart failure	NR	NR
Results	Unadjusted (statin n/N) 41/1810, PS matched (statin n/N) 35/1786; Unadjusted (non-statin n/N) 56/3196, PS Matched (non-statin n/N) 48/1786	OR = 1.03, 95%CI: 0.90-1.18, P = 0.80	Statin (n/N) 8/137; Non-statin (n/N) 3/67

COPD: Chronic obstructive pulmonary disease; n/N: Number of events/total number of individuals in the group; PS: Propensity score; NR: Not reported; OR: Odds ratio; CI: Confidence interval.

Table 3 Comparative overview of the outcomes: 30-day mortality

	Pourlotfi et al[9]	Disbrow et al[10]	Fransgaard et al[11]
Statin therapy definition	User defined as redeeming 1 or more statin prescriptions 1 year before surgery; postoperative continuation period not stated	Ongoing statin therapy No information reported of statin duration of use	Statin user defined as redeeming 2 or more statin prescriptions 1 year before surgery; postoperative continuation period not stated
Type of surgical data	Rectal cancer only	Colectomy and rectal resection combined and separate	Combined colorectal
Surgical procedure	Anterior resection; abdominoperineal resection Hartmann’s operation
Comorbidities	Diabetes; COPD; liver disease, hypertension; congestive heart failure	Diabetes; COPD; ascites/cirrhosis; hypertension; congestive heart failure
Results	Unadjusted (statin n/N) 8/3019, PS matched (statin n/N) 8/3017; unadjusted (non-statin n/N) 8/3017, PS matched (non-statin n/N) 112/3017	Unadjusted (statin n/N) 27/2515, PS matched (statin n/N) 12/1786; unadjusted (non-statin n/N) 35/4770; PS matched (non-statin n/N) 24/1786	Statin (n/N) 316/5961; non-statin (n/N) 1347/23391

COPD: Chronic obstructive pulmonary disease; n/N: Number of events/total number of individuals in the group; PS: Propensity score.

Table 4 Comparative overview of the outcomes: 90-day mortality

	Pourlotfi et al[9]	Löffler et al[16]
Statin therapy definition	User defined as redeeming 1 or more statin prescriptions 1 year before surgery; postoperative continuation period not stated	Prescribed statins with prescriptions active or in use during the period spanning up to 365 days before surgery
Type of surgical data	Rectal cancer only	Colectomy and rectal resection combined and separate
Surgical procedure	Anterior resection; abdominoperineal resection Hartmann’s operation
Comorbidities	Diabetes; COPD; liver disease, hypertension; congestive heart failure
Results	Unadjusted (statin n/N) 20/3019, PS matched (statin n/N) 20/3017; unadjusted (non-statin n/N) 291/8947, PS matched (non-statin n/N) 166/3017	Statin (n/N) 217/3654; non-statin (n/N) 242/3654

COPD: Chronic obstructive pulmonary disease; n/N: Number of events/total number of individuals in the group; PS: Propensity score.