Retrospective comparison of open vs minimally invasive cystotomy in 28 cats using a composite outcome score

The aim of this study was to compare the outcomes of cats undergoing open cystotomy with those undergoing minimally invasive surgery (MIS) for removal of cystic calculi by use of a composite outcome score.

Twenty-eight cats were retrospectively enrolled and divided into two groups: open cystotomy (n = 14) and MIS (n = 14). The primary outcome measure was a composite outcome score, including three variables: pain scores ⩾2 at either 6 or 12 h postoperatively; failure to remove all stones as determined by postoperative radiographs; and postoperative complications requiring a visit to the hospital separate from the planned suture removal appointment. Other data collected included signalment, history, other procedures performed during anesthesia, willingness to eat the day after surgery and the financial cost of the procedures.

There was no significant difference in age, weight, sex or breed between the two groups. The risk of experiencing the composite outcome was 3/14 (21.4%) in the MIS group and 10/14 (71%) in the open procedure group (P = 0.02). The cats in the open surgery group had 8.3 times greater odds of developing the composite outcome than cats in the MIS group (odds ratio 8.3, 95% confidence interval 1.3-74.4; P = 0.02). In the MIS group, 10/14 cats were eating the day after surgery vs 3/14 in the open procedure group (P = 0.02). The procedural cost was higher in the MIS group, with a median cost of US$945 (interquartile range [IQR] US$872-1021) vs US$623 (IQR US$595-679) in the open group (P <0.01).

In this study the composite outcome score provided evidence to support the use of MIS techniques in cats with cystic calculi. The composite outcome score should be considered in future veterinary studies as a promising method of assessing clinically relevant outcomes.