Background: The clinical diagnosis of appendicitis is a subjective synthesis of information from variables with ill-defined diagnostic value. This process could be improved by using a scoring system that includes objective variables that reflect the inflammatory response. This study describes the construction and evaluation of a new clinical appendicitis score. Methods: Data were collected prospectively from 545 patients admitted for suspected appendicitis at four hospitals. The score was constructed from eight variables with independent diagnostic value (right-lower-quadrant pain, rebound tenderness, muscular defense, WBC count, proportion neutrophils, CRP, body temperature, and vomiting) in 316 randomly selected patients and evaluated on the remaining 229 patients. Ordered logistic regression was used to obtain a high discriminating power with focus on advanced appendicitis. Diagnostic performance was compared with the Alvarado score. Results: The ROC area of the new score was 0.97 for advanced appendicitis and 0.93 for all appendicitis compared with 0.92 (p = 0.0027) and 0.88 (p = 0.0007), respectively, for the Alvarado score. Sixty-three percent of the patients were classified into the low- or high-probability group with an accuracy of 97.2%, leaving 37% for further investigation. Seventy-three percent of the nonappendicitis patients, 67% of the advanced appendicitis, and 37% of all appendicitis patients were correctly classified into the low- and high-probability zone, respectively. Conclusion: This simple clinical score can correctly classify the majority of patients with suspected appendicitis, leaving the need for diagnostic imaging or diagnostic laparoscopy to the smaller group of patients with an indeterminate scoring result. © 2008 Société Internationale de Chirurgie.

The diagnosis of appendicitis is difficult and resource consuming. New inflammatory markers have been proposed for the diagnosis of appendicitis, but their utility in combination with traditional diagnostic variables has not been tested. Our objective is to explore the potential of new inflammatory markers for improving the diagnosis of appendicitis. The diagnostic properties of the six most promising out of 21 new inflammatory markers (interleukin [IL]-6, chemokine ligand [CXCL]-8, chemokine C-C motif ligand [CCL]-2, serum amyloid A [SAA], matrix metalloproteinase [MMP]-9, and myeloperoxidase [MPO]) were compared with traditional diagnostic variables included in the Appendicitis Inflammatory Response (AIR) score (right iliac fossa pain, vomiting, rebound tenderness, guarding, white blood cell [WBC] count, proportion neutrophils, C-reactive protein and body temperature) in 432 patients with suspected appendicitis by uni- and multivariable regression models. Of the new inflammatory variables, SAA, MPO, and MMP9 were the strongest discriminators for all appendicitis (receiver operating characteristics [ROC] 0.71) and SAA was the strongest discriminator for advanced appendicitis (ROC 0.80) compared with defence or rebound tenderness, which were the strongest traditional discriminators for all appendicitis (ROC 0.84) and the WBC count for advanced appendicitis (ROC 0.89). CCL2 was the strongest independent discriminator beside the AIR score variables in a multivariable model. The AIR score had an ROC area of 0.91 and could correctly classify 58.3 % of the patients, with an accuracy of 92.9 %. This was not improved by inclusion of the new inflammatory markers. The conventional diagnostic variables for appendicitis, as combined in the AIR score, is an efficient screening instrument for classifying patients as low-, indeterminate-, or high-risk for appendicitis. The addition of the new inflammatory variables did not improve diagnostic performance further.

Background

The management of patients with suspected appendicitis is highly variable with implications for the rate of diagnostic errors, unnecessary admissions and resource consumption. We hypothesise that a structured management algorithm based on the Appendicitis Inflammatory Response (AIR) score can improve diagnostic accuracy, limit the use of diagnostic imaging, and reduce the number of hospital admissions for patients with suspected appendicitis.

Methods

Prospective interventional multicentre study. Patients at 25 Swedish hospitals over the age of five, presenting with suspected appendicitis at the emergency department were considered for inclusion. After an initial period of routine management and registration of the AIR score parameters (baseline period), an AIR-score-based management algorithm was implemented (intervention period). The study analyses the discriminating capacity and predictive value of the AIR score and the impact of implementing the AIR-score-based algorithm.

Results

In total, 3791 patients were included. Advanced appendicitis is unlikely at an AIR score <5 points (sensitivity 0.96), and appendicitis is likely at an AIR score >8 (specificity 0.98). The implementation of the AIR-score-based algorithm resulted in fewer negative explorations and operations for phlegmonous appendicitis (1.6% vs 3.4%, p=0.019 and 5.5% vs 9.4%, p=0.003, respectively), a reduction in admissions to hospital and use of imaging (29.5% vs 42.8%, p<0.001 and 19.2% vs 34.5%, respectively), and no difference with regard to advanced appendicitis in the low-risk group, and a decrease in the use of diagnostic imaging in the high-risk group (38.5% vs 53.1%, p=0.021).

Conclusions

The AIR score has high discriminating capacity. Implementing an AIR-score-based algorithm increased diagnostic accuracy and lowered the use of diagnostic imaging and in-hospital observation.

Background

Diagnostic imaging is increasingly used in patients with suspected appendicitis, with increased costs and concerns about exposure to ionising radiation. Indications suggest that routine imaging is associated with a higher detection rate and treatment of potentially resolving appendicitis. The efficiency of routine imaging compared with in-hospital observation and selective imaging is not well studied.

Methods

The proportions of negative appendectomy and treatments for appendicitis are studied in 1068 patients with intermediate suspicion of appendicitis, indicated by an Appendicitis Inflammatory Response (AIR) score sum of five to eight points, randomly allocated by opaque sealed envelopes to early routine diagnostic imaging (Imaging group, n=543) or re-assessment after 4–8 hours inhospital observation followed by selective diagnostic imaging (Observation group, n=525). Some 21 hospitals in Sweden participated in this multicentre study.

Findings

The Imaging and Observation groups had the same proportion of negative appendectomies (6·5% in both, difference 0·03%, CI –3·0%–3·1%, p=0·98) but routine imaging was associated with an increased proportion of patients treated for appendicitis (53·4% vs 46·3%, difference  7·1%, CI 1·0–13·2%, p=0·020). As secondary outcomes, the Imaging group had shorter time to surgery (median 13·7 hours vs 15·5 hours, p<0·01), but no difference in admissions, number of perforations or length of hospital stay.

Interpretation

Patients with suspected appendicitis and equivocal clinical findings do not benefit from early routine diagnostic imaging compared with re-assessment after observation and selective imaging. The latter is associated with fewer operations for non-perforated appendicitis which supports the hypothesis of resolving appendicitis.