The present study shows an elevated success rate of non-operative treatment among immunosuppressed patients with an episode of complicated acute diverticulitis associating a pericolic or pelvic abscess (81.3% among the IMS groups vs. 92.0% among the IC group, p = 0.178).
Recently there have been publications on satisfactory results of medical treatment of non-complicated left-sided diverticulitis in immunocompromised patients12,13. However, we are not yet in possession of results on ALCD complicated with an abscess (modified HincheyIb/II) in this subgroup of patients. The overall success rate of medical treatment in immunocompetent patients exceeds 80% in current literature18,19, which is why it remains the treatment of choice according to different guidelines4,5,17. These guidelines however present no recommendations on management in immunosuppressed patients.
The rate of emergency surgery was far superior in the IMS group (50.0 vs. 22.5%, p < 0.001), due to a high percentage of modified Hinchey III and IV patients. Nevertheless, emergent surgery was also more frequent in the subgroup of patients with an associated abscess, even though there were no significant differences neither in the overall success of medical treatment (p = 0.178) nor in the rate of deferred surgery during admission due to unsuccessful medical treatment (12.1% vs. 12.0%).
Hartmann´s procedure was the most common approach among the IMS group (86.2%), comparable with other published series: 65.2%10; 79.2%20;91.4%9. Hartmann´s procedure was also the most common intervention among the IC group. Even though the current recommendations tend to encourage primary anastomosis with or without temporary diverting stoma in hemodynamically stable patients with no significant comorbidities4,17, in the majority of published series a colonic resection with an end colostomy continues to be the most common procedure, with higher rates than in our study21,22.
The current study shows high rates of morbidity (72.4%) and early mortality (24.1%) among the IMS group, yet tantamount with the current literature – morbidity of 7010-81.8%21and mortality of 19.210-33%7.
In a recent systematic review of 1599 immunocompromised patients submitted to emergency surgery, the rate of mortality was far superior in the IMS group (RR 1.9, p < 0.001)23. The same review analyzed the results of elective surgery encountering greater morbidity among the IMS patients (RR 2.18 p = 0.04), without differences in the postoperative mortality. A retrospective multicentric review of Al-Khamis et al.9 included 736 immunocompromised patients and 21980 immunocompetent and found no morbidity differences between a scheduled sigmoidectomy (OR 1.45) and Hartmann´s procedure (29.2% versus 10.5%, p < 0.001).
The high rate of definitive stoma in the IMS group is an important factor to consider (IMS 82.1% vs. IC 29.9%, p < 0.001, at the end of the follow-up), which underlines the low rate of stoma reversal in this group of patients, partially due to high surgical risk even in scheduled surgery.
On the other hand, the IMS patients have always been considered a high-risk group for complex recurrences, regardless of the initial staging of diverticulitis6,9,24and therefore for emergent surgery of the recurrence5,24.Klarenbeek B et al.24 describe a 5 fold higher rate of perforation in the recurrent episode in comparison with the IC patients (36% vs. 7%, p = 0.002). On the contrary, other, more recent series present us with lower recurrence rates (12-27.8%)7,25,26. This is why multiple guidelines recommend submitting the IMS patients to scheduled surgery once they have recovered from the initial episode, regardless of the initial staging5,17,27. However, recent studies questioned this indication in cases of non-complicated diverticulitis7,12, which led to modifications in the recent ASCRS guideline for this subgroup of patients4, providing a change in comparison to its´ previous edition27and in comparison to other guidelines5,17.
Biondoet al7 in a retrospective study comparing 107 IMS vs. 657 IC patients (including non-complicated and complicated episodes of diverticulitis) found no differences in the recurrence rates (21.5% IMS vs. 20.5%, respectively, P = 0.82), rate of emergent surgery of the recurrence (17.4% IND vs. 15%, P = 0.77), after a mean follow-up of 81.6 months. They did find a higher recurrence rate in the IMS patients with an initial episode of ALCD(46.2%, 12/26 patients). The authors concluded that there was no need for scheduled surgery following a non-complicated episode of diverticulitis in IMS patients.
In the present study we found no significant differences in the recurrence rate following a ALCD with an abscess formation, with recurrence of 31.2% in the IMS group vs. 35.4% in the IC group (p = 0.698). Also, no differences were found in the rate of emergent surgery of the recurrence (p = 0.063). 81.2% (13/16) of the IMS patients following a medically managed ALCD did not need surgery at the end of the follow-up, comparable with the IC group (p 0.148). We also did not find differences between both groups while analyzing the subgroup of patients with ALCD with localized pneumoperitoneum, without a formed abscess − 84.2% did not need surgery at the end of follow-up. These results may question the need for deferred surgery in this subgroup of patients, in contrary to other authors21,24,26,28,29 and guidelines5,17.
The majority of recent studies analyzing the results of immunosupressed patients with an episode of acute diverticulitis do not take into account the severity of the episode, most of them include non-complicated episodes10,13,23.In the present study, only complicated episodes were analyzed. Even though there are many conditions which may affect our immune system with distinct severity, for the purpose of our study only severely immunocompromised patients were considered (solid organ transplant; active oncological treatment; steroid treatment; end stage kidney failure on hemodialysis)15,29. Whether or not the specific cause of immunosuppression should influence treatment recommendations remainsunknown4.In our study no differences were found between the different subgroups of immunocompromised patients. As it was a unicentric study and the database began following a new protocol establishment, there were no notable differences in treatment approach. As limitations we may state the retrospective analysis and the number of patients included.
Medical treatment of immunosuppressed patients during their first ALCD associating an abscess is feasible, with a high success rate and results comparable with the IC group. Moreover, taking into account the readmission rates, the need of emergent surgery of the recurrence, as well as the perioperative mortality and morbidity in the IMS group, conservative management with no differed scheduled surgery seems to be a safe option in this subgroup of patients.