Abstract
INTRODUCTIONThe negative appendicectomy rate (NAR) is a quality metric in the management of appendicitis. While computed tomography (CT) has been associated with a low NAR, Alvarado scoring produces an acceptable NAR. The definition of negative appendicectomy may affect the NAR. This study examined the impact of CT, Alvarado score and definition on the NAR.METHODSThe charts of 1,306 emergency appendicectomy patients from 1996 to 2010 were reviewed. Three five-year cohorts were created (Cohort A: 1996–2000, Cohort B: 2001–2005, Cohort C: 2006–2010) and the NAR was calculated for each cohort using two definitions of negative appendicectomy: absence of inflammation (NAR-STD) and absence of intramural neutrophils (NAR-STR). NAR-STD was correlated to the CT rate for Cohorts B and C and also to Alvarado score for Cohort C.RESULTSWhen the definition of negative appendicectomy was changed, the NAR rose from 9.2% to 15.8% (p=0.0097) for Cohort A, from 2.8% to 8.6% (p=0.0180) for Cohort B (CT rate: 80.6%) and from 3.0% to 6.7% (p=0.0255) for Cohort C (CT rate: 92.4%). The introduction of CT lowered NAR-STD from 1996–2000 (9.2%) to 2001–2010 (2.9%) but increasing the CT rate from 2001–2010 had no impact on the NAR. The positive predictive value for Alvarado score (98.60%) and CT (99.03%) were similar.CONCLUSIONSThe definition of a negative appendicectomy determines the NAR. CT reduces the NAR regardless of definition but routine CT is unnecessary for male patients with positive Alvarado scores. Early/mild appendicitis may resolve without surgery and CT may contribute to unnecessary surgery. Alvarado scoring allows selective use of CT in suspected appendicitis.
Highlights
The negative appendicectomy rate (NAR) is a quality metric in the management of appendicitis
Changing the definition from NARs were compared using standard criteria (NAR-STD) to NAR with a more stringent definition (NAR-STR) increased the overall NAR from 9.2% to 15.8%, a significant change (p=0.0097)
While computed tomography (CT) use was beneficial in lowering the NAR from the 9.2% of the pre-CT era (1996–2000) to 3.0% in the subsequent periods (2001–2010) (p=0.0120), the increasing CT rate from 66% to 98% did not further reduce NAR-STD
Summary
The negative appendicectomy rate (NAR) is a quality metric in the management of appendicitis. This study examined the impact of CT, Alvarado score and definition on the NAR. Three five-year cohorts were created (Cohort A: 1996–2000, Cohort B: 2001–2005, Cohort C: 2006–2010) and the NAR was calculated for each cohort using two definitions of negative appendicectomy: absence of inflammation (NAR-STD) and absence of intramural neutrophils (NAR-STR). NAR-STD was correlated to the CT rate for Cohorts B and C and to Alvarado score for Cohort C. The introduction of CT lowered NAR-STD from 1996–2000 (9.2%) to 2001–2010 (2.9%) but increasing the CT rate from 2001–2010 had no impact on the NAR. CT reduces the NAR regardless of definition but routine CT is unnecessary for male patients with positive Alvarado scores. Alvarado scoring allows selective use of CT in suspected appendicitis
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