Meaningful standard of reference for appendiceal perforation: pathology, surgery, or both?

Low-Dose Abdominal CT for Evaluating Suspected Appendicitis in Adolescents and Young Adults: Review of Evidence

Due to its excellent diagnostic performance, CT is the mainstay of diagnostic test in adults with suspected acute appendicitis in many countries. Although debatable, extensive epidemiological studies have suggested that CT radiation is carcinogenic, at least in children and adolescents. Setting aside the debate over the carcinogenic risk of CT radiation, the value of judicious use of CT radiation cannot be overstated for the diagnosis of appendicitis, considering that appendicitis is a very common disease, and that the vast majority of patients with suspected acute appendicitis are adolescents and young adults with average life expectancies. Given the accumulated evidence justifying the use of low-dose CT (LDCT) of only 2 mSv, there is no reasonable basis to insist on using radiation dose of multi-purpose abdominal CT for the diagnosis of appendicitis, particularly in adolescents and young adults. Published data strongly suggest that LDCT is comparable to conventional dose CT in terms of clinical outcomes and diagnostic performance. In this narrative review, we will discuss such evidence for reducing CT radiation in adolescents and young adults with suspected appendicitis.

Final diagnosis and patient disposition following equivocal results on 2-mSv CT vs. conventional-dose CT in adolescents and young adults with suspected appendicitis: a post hoc analysis of large pragmatic randomized trial data

OBJECTIVE

To compare 2-mSv CT and conventional-dose CT (CDCT, typically 7-8 mSv) regarding final diagnosis and patient disposition following equivocal CT results in adolescents and young adults with suspected appendicitis.

METHODS

In total, 3074 patients of 15-44 years (28 ± 9 years, 1672 women) from 20 hospitals were randomized to undergo contrast-enhanced 2-mSv CT (n = 1535) or CDCT (n = 1539) from December 2013 through August 2016. One hundred sixty-one radiologists prospectively rated the likelihood of appendicitis in a Likert scale (i.e., grades 1-5). The final diagnosis was based on CT image, surgical, pathologic, and clinical findings. Post hoc analysis was performed for final diagnosis, surgical procedure, and delay in patient management following equivocal results (i.e., grade 3).

RESULTS

The 2-mSv CT and CDCT groups were comparable for final diagnosis following equivocal results, including confirmed appendicitis (1.2% [18 patients] vs. 1.2% [19], p > 0.99), negative appendectomy (0.1% [2] vs. 0.3% [4], p = 0.53), and perforated appendicitis (0.1% [1] vs. 0.2% [3], p = 0.53). More patients were confirmed as not having appendicitis following equivocal results in the CDCT group than in the 2-mSv CT group (2.2% [34] vs. 1.0% [16], p = 0.016). The two groups were comparable for the need of appendectomy (1.4% [22] vs. 1.5% [23], p > 0.99), need of additional imaging tests (0.7% [11] vs. 1.1% [17], p = 0.35), and delay in patient management following equivocal results.

CONCLUSION

2-mSv CT is comparable to CDCT regarding final diagnosis and patient disposition following equivocal CT results.

KEY POINTS

• Our results strengthen evidence justifying the use of low-dose CT instead of conventional-dose CT (CDCT) in adolescents and young adults with suspected appendicitis. • The 2-mSv CT and CDCT groups were comparable for final diagnosis following equivocal CT results, including confirmed appendicitis (1.2% vs. 1.2%, p > 0.99), negative appendectomy (0.1% vs. 0.3%, p = 0.53), and perforated appendicitis (0.1% vs. 0.2%, p = 0.53). • The two groups were comparable for the need for appendectomy (1.4% vs. 1.5%, p > 0.99), need for additional imaging tests (0.7% vs. 1.1%, p = 0.35), and delay in patient management, following equivocal CT results.

Differentiation between complicated and uncomplicated appendicitis: diagnostic model development and validation study

PURPOSE

Differentiating complicated appendicitis has become important, as multiple trials showed that non-operative management of uncomplicated appendicitis is feasible. We developed and validated a diagnostic model to differentiate complicated from uncomplicated appendicitis.

METHODS

This retrospective study included 1153 patients (mean age ± standard deviation, 30 ± 8 years) with appendicitis on CT (804 patients for development, and 349 for validation). Complicated appendicitis was confirmed in 300 and 121 patients in the development and validation datasets, respectively. The reference standard was surgical or pathological report except in 7 patients who underwent percutaneous abscess drainage. We developed a model using multivariable logistic regression and Bayesian information criterion. We assessed calibration and discriminatory performance of the model in the validation dataset via calibration plot and the area under the curve (AUC), respectively. We measured sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and proportion of false- and true-negatives of the model in the validation dataset, targeting 95% sensitivity.

RESULTS

Five CT features (contrast-enhancement defect of the appendiceal wall, abscess, moderate or severe periappendiceal fat stranding, appendiceal diameter, and extraluminal air) and percentage of segmented neutrophil were included in our model. The calibration slope was 1.03, and AUC was 0.81 (95% CI 0.77-0.85) in the validation dataset. The sensitivity, specificity, PPV, NPV, and proportion of false- and true-negatives were 93.4% (91.8-99.1), 28.1% (13.6-24.1), 40.8% (35.0-46.8), 88.9% (79.3-95.1), 2.3%, and 18.3%, respectively.

CONCLUSION

Our model may identify patients with unequivocally uncomplicated appendicitis, who may benefit from non-operative management with low risk of failure.

Development and Implications of an Evidence-based and Public Health-relevant Definition of Complicated Appendicitis in Children

OBJECTIVE

To characterize the influence of intraoperative findings on complications and resource utilization as a means to establish an evidence-based and public health-relevant definition for complicated appendicitis.

SUMMARY OF BACKGROUND DATA

Consensus is lacking surrounding the definition of complicated appendicitis in children. Establishment of a consensus definition may have implications for standardizing the reporting of clinical research data and for refining reimbursement guidelines.

METHODS

This was a retrospective cohort study of patients ages 3 to 18 years who underwent appendectomy from January 1, 2013 to December 31, 2014 across 22 children's hospitals (n = 5002). Intraoperative findings and clinical data from the National Surgical Quality Improvement Program-Pediatric Appendectomy Pilot Database were merged with cost data from the Pediatric Health Information System Database. Multivariable regression was used to examine the influence of 4 intraoperative findings [visible hole (VH), diffuse fibrinopurulent exudate (DFE) extending outside the right lower quadrant (RLQ)/pelvis, abscess, and extra-luminal fecalith] on complication rates and resource utilization after controlling for patient and hospital-level characteristics.

RESULTS

At least 1 of the 4 intraoperative findings was reported in 26.6% (1333/5002) of all cases. Following adjustment, each of the 4 findings was independently associated with higher rates of adverse events compared with cases where the findings were absent (VH: OR 5.57 [95% CI 3.48-8.93], DFE: OR 4.65[95% CI 2.91-7.42], abscess: OR 8.96[95% CI 5.33-15.08], P < 0.0001, fecalith: OR 5.01[95% CI 2.02-12.43], P = 0.001), and higher rates of revisits (VH: OR 2.02 [95% CI 1.34-3.04], P = 0.001, DFE: OR 1.59[95% CI 1.07-2.37], P = 0.02, abscess: OR 2.04[95% CI 1.2-3.49], P = 0.01, fecalith: OR 2.31[95% CI 1.06-5.02], P = 0.04). Each of the 4 findings was also independently associated with increased resource utilization, including longer cumulative length of stay (VH: Rate ratio [RR] 3.15[95% CI 2.86-3.46], DFE: RR 3.06 [95% CI 2.83-3.13], abscess: RR 3.94 [95% CI 3.55-4.37], fecalith: RR 2.35 [95% CI 1.87-2.96], P =  < 0.0001) and higher cumulative hospital cost (VH: RR 1.97[95% CI 1.64-2.37], P < 0.0001, DFE: RR 1.8[95% CI 1.55-2.08], P =  < 0.0001, abscess: RR 2.02[95% CI 1.61-2.53], P < 0.0001, fecalith: RR 1.49[95% CI 0.98-2.28], P = 0.06) compared with cases where the findings were absent.

CONCLUSION AND RELEVANCE

The presence of a visible hole, diffuse fibrinopurulent exudate, intra-abdominal abscess, and extraluminal fecalith were independently associated with markedly worse outcomes and higher cost in children with appendicitis. The results of this study provide an evidence-based and public health-relevant framework for defining complicated appendicitis in children.

Diagnostic sensitivity and specificity of 2-mSv CT vs. conventional-dose CT in adolescents and young adults with suspected appendicitis: post hoc subgroup analysis of the LOCAT data

OBJECTIVES

To test whether the difference in sensitivity or specificity between 2-mSv CT and conventional-dose CT (CDCT) for the diagnosis of appendicitis differs across subgroups of adolescents and young adults with suspected appendicitis.

MATERIALS AND METHODS

We used the per-protocol analysis data of a trial conducted between Dec 2013 and Aug 2016, including 2773 patients (median age [interquartile range], 28 [21-35] years) and 160 radiologists from 20 hospitals. We defined subgroups by sex, body size, clinical risk scores for appendicitis, time of CT examination (i.e., working vs. after hours), CT machines, radiologists' experience, previous site experience in 2-mSv CT, and site practice volume. We drew forest plots and tested for additive or multiplicative interaction between radiation dose and subgroup attributes. If any subgroup had fewer than 200 patients, we considered the results from that subgroup not meaningful.

RESULTS

For most subgroups, the 95% CIs for the differences in sensitivity and specificity were 4.0 percentage points or narrower and contained the minute overall between-group differences. There was no significant interaction on sensitivity or specificity. A few subgroups, including those of extreme body sizes, high appendicitis inflammatory response scores, and hospitals with small appendectomy volume, were regarded to have insufficient numbers of patients.

CONCLUSIONS

There was no notable subgroup heterogeneity, which implies that 2-mSv CT can replace CDCT in diverse populations. Further studies are needed for the subgroups for which we had only small data.

KEY POINTS

• The minute difference in sensitivity or specificity between the 2-mSv CT and conventional-dose CT (typically 7 mSv) groups were consistent across various patient or hospital characteristics. • These results indicate that 2-mSv CT can replace conventional-dose CT in diverse populations. • Further studies are needed to confirm whether 2-mSv CT can replace conventional-dose CT in patients of extreme body sizes, high appendicitis inflammatory response scores, or hospitals with small appendectomy volume, as those subgroups in our data included limited numbers of patients.