This prospective series demonstrates that standard clinical evaluation, by non-specialist doctors, provides a high degree of diagnostic precision in patients with acute colonic diverticulitis. The diagnostic precision was slightly higher among patients younger than 65 years compared to those older. Furthermore, the analyses proved CRP to be the most valuable initial laboratory test in the differentiation of acute diverticulitis from other acute abdominal conditions.
Relation to other reports
Few reports have used ROC curve analysis to assess the clinical diagnostic performance in acute colonic diverticulitis [8, 32]; a categorical scoring system similar to the one presented here has never been used. In order to compare our findings with previous studies regarding sensitivity and specificity, we chose a cutoff value of 6 on the scale from 0 to 10. The resulting sensitivities and specificities were in accordance with previous studies that reported a sensitivity of 64–71 % and a specificity of 97–98 % when evaluating clinical diagnostics in acute colonic diverticulitis [8, 9, 22–25].
The clinical diagnostic sensitivity of acute colonic diverticulitis, based on examinations before admission to hospital by the primary care physicians, was 52 %. This was inferior to the results achieved by the non-specialist doctors in the hospital, but comparable to a previous study on diagnostic sensitivity of acute colonic diverticulitis in primary health care . Various factors have impact on this finding: increased focus on patients with acute colonic diverticulitis, because of the study and the selection of patients admitted to a surgical department, advantage of the tentative diagnosis from the primary care physicians, and access to previous hospital records, body temperature, and blood tests in all included cases.
In the present study, the accuracy of the clinical diagnosis was slightly better in younger patients. The presentation of acute abdominal pain among elderly may be different from that seen in younger age groups. Elderly patients tend to have more vague and non-specific symptoms, broader alternatives of differential diagnosis, altered clinical signs that do not correlate with disease severity, higher incidence of comorbidity and multi-pharmacy, and communication difficulties because of hearing and cognitive impairment [26, 27]. This makes elderly patients more prone to misdiagnosis than younger patients .
ROC curve analysis to assess CRP in the diagnostics of acute colonic diverticulitis has previously been reported with an AUC ranging from 0.72 to 0.94 [8, 30–34], which is comparable to the present results. Furthermore, these studies confirm WBC count and body temperature to be without discriminative power in distinguishing diverticulitis from other patients with acute abdominal pain, with an AUC between 0.54 and 0.57 [8, 33].
Most previous studies have focused on these parameters in the differentiation between uncomplicated and complicated acute colonic diverticulitis [29, 32, 33]; also demonstrating that CRP, other than WBC count, was the most important biochemical marker.
This study confirms that a clinical diagnosis of acute colonic diverticulitis is achievable by non-specialist doctors at the emergency department and applies specifically to patients younger than 65 years with localized tenderness in the left lower quadrant and an elevated CRP.
Previous studies report other criteria as significant in the selection of patients suitable for out-patient diagnosis and treatment such as a CRP cutoff value between 150 and 200 mg/L, absence of vomiting, significant fever and signs of generalized peritonitis, absence of compromised immune status, and significant comorbidities. Of additional importance is a close follow-up and the possibility of a secondary evaluation if symptoms worsen [8, 31–37]. The diagnosis would be even more strengthened in patients who have recurrent symptoms, with colonic diverticular disease verified on a pervious CT scan.
Out-patient treatment would include oral analgesics, with or without oral antibiotics. Follow-up, including clinical examination and CRP with the possibility of ambulant CT scan on day 4 and referral to follow-up endoscopy or CT colonography after 6 weeks of improvement, has been suggested .
This evidence should form the basis for a clinical care pathway. A structural approach, involving both the primary and secondary healthcare system, would increase the quality of treatment, define an appropriate level of treatment for the individual patient, and reduce the increasing rates of admission to hospital among patients with acute colonic diverticulitis.
Weakness of the study
Not all patients admitted to hospital because of acute abdominal pain in the study period were included in this study. There were no statistical differences in gender, age, subtype of acute colonic diverticulitis, or hospital stay when comparing patients included or not, as shown in Table 1. The included patients seem to be a representative selection of all patients admitted with acute abdominal pain, although a more complete inclusion would have increased the precision of the findings.
Another limitation is the probable selection bias based on the hospital doctors’ awareness of the study. However, the percentage of patients with acute colonic diverticulitis in relation to other types of acute abdomen conditions generally matches other studies .
Strengths of the study
The present prospective study is the first to use a fine graded categorized clinical score and subsequent ROC curve analysis in the evaluation of clinical diagnostic accuracy in patients with acute colonic diverticulitis. The advantage of ROC curve analysis in the present study was the possibility to consider the complete spectrum of the observed results, not only the mean or dichotomous variable denoting “yes or no.”
The study highlights that non-specialist doctors, usually in their first year of a clinical career, were able to clinically diagnose acute colonic diverticulitis in patients with acute abdominal pain with a high degree of accuracy. This reflects the possibility of a similar standardized approach applied in the out-patient setting, reducing the need for further referral to hospitals, especially in cases of suspected uncomplicated acute colonic diverticulitis.