The CUSUM Slope Equals Observed Minus Expected Mortality and Can Be Visualized by a "Slope-Meter".

We present an additional advantage of the Risk-Adjusted CUSUM (RA-CUSUM), namely, that its slope can be quantified and is in fact equivalent to Observed (O) minus Expected (E) mortality. That is, the height of the RA-CUSUM is the O minus E deaths, which measures performance since the start of the series, and the slope of the RA-CUSUM is the O minus E mortality which measures performance during a chosen interval. We present a useful graphical tool (Slope-Meter) to allow approximation of this mortality difference by the viewer.

Temporal trends and predictors of surgical ablation for atrial fibrillation across a multistate healthcare system.

BACKGROUND: Multiple class I and class IIa recommendations exist related to surgical ablation (SA) of atrial fibrillation (AF) in patients undergoing cardiac surgery. OBJECTIVE: Examine temporal trends and predictors of SA for AF in a large US healthcare system. METHODS: We retrospectively analyzed data from the Society for Thoracic Surgery (STS) Adult Cardiac Surgery Database for 21 hospitals in the Providence St. Joseph Health system. All patients with preoperative AF who underwent isolated coronary artery bypass graft (CABG) surgery, isolated aortic valve replacement (AVR), AVR with CABG surgery (AVR+CABG), isolated mitral valve repair or replacement (MVRr), and MVRr with CABG surgery (MVRr+CABG) from July 1, 2014, to March 31, 2020 were included. Temporal trends in SA were evaluated using the Cochran-Armitage trends test. A multilevel logistic regression model was used to examine patient-, hospital-, and surgeon-level predictors of SA. RESULTS: Among 3124 patients with preoperative AF, 910 (29.1%) underwent SA. This was performed most often in those undergoing isolated MVRr (n = 324, 44.8%) or MVRr+CABG (n = 75, 35.2%). Rates of SA increased over time and were highly variable between hospitals. Years since graduation from medical school for the primary operator was one of the few predictors of SA: odds ratio (95% confidence interval) = 0.71 (0.56-0.90) for every 10-year increase. Annual surgical (both hospital and operator) and AF catheter ablation volumes were not predictive of SA. CONCLUSION: Wide variability in rates of SA for AF exist, underscoring the need for greater preoperative collaboration between cardiologists, electrophysiologists, and cardiac surgeons.

A multi-institutional approach for decreasing narcotic prescriptions after laparoscopic appendectomy.

BACKGROUND: Appendicitis is a common indication for surgical hospital admission. Uncomplicated appendicitis is typically treated with surgical intervention, most commonly a laparoscopic appendectomy. As with many procedures, narcotic utilization is highly varied among surgeons for postoperative pain control. With the opioid epidemic and a demonstrated link between excessive narcotic prescriptions paving the way to dependence and addiction, it is more important than ever to decrease the circulation of these medications. We hypothesized that a perioperative, multimodal analgesia strategy coupled with monthly feedback reports comparing hospitals narcotic prescribing habits would decrease, and in some cases eliminate, the use of outpatient narcotics in adults after laparoscopic appendectomy. METHODS: A quality improvement project was initiated to provide monthly feedback to surgeons on narcotic prescribing habits after adult laparoscopic appendectomies. A multi-hospital database was created to include adult patients that were diagnosed with acute appendicitis, treated with laparoscopic appendectomy, and discharged within 48 h of surgery. The database provided information regarding the number of narcotic doses prescribed on discharge. Participating hospitals selected a site champion who distributed monthly prescribing reports. A protocol was created and distributed to participating sites that provided a guideline for preoperative and postoperative pain medication management. The intervention period was 10/1/2019-3/31/2020. We utilized the preceding year's data (October 1, 2018-September 30, 2019) as the pre-intervention control group. We also compared results between local and distant sites to see if personal connection to surgeons influenced the results. RESULTS: A total of 1785 appendectomies were performed during the study period at participating hospitals. The average number of prescribed narcotics decreased from 23.6 doses during the control period to 14.2 during the intervention (p < 0.001). There was no change in the number of total narcotic prescriptions (8.9 vs 7.9%, p = 0.52). Overall, the average number of narcotics prescribed decreased by 40% with similar decrease in average prescribed narcotics for local and distant hospitals, respectively (47.7% vs 42.1%). Average narcotic dose during the first 2 months of intervention at the local hospitals was 9.7 and 11.1 for the last 2 months of intervention (p = 0.69). Average narcotic dose during the first 2 months of intervention at the distant hospitals was 19.5 and 13.4 for the last 2 months of intervention (p = 0.005). CONCLUSION: A multimodal pain regimen combined with a monthly narcotic prescription report provided to prescribers decreases the average number of narcotic prescriptions after laparoscopic appendectomy. Local sites demonstrated immediate decrease in narcotic utilization compared to distant sites whose change occurred more gradually.

Calibration Factors for STS Risk Model Predictions: Why, How and When They Are Used.

The Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database is the world's premier adult cardiac surgery outcomes registry. This tutorial explains the following: how STS updates the risk models that are used to calculate the predicted risks of adverse events in the registry; why STS on a quarterly basis adjusts or "calibrates" the observed-to-expected ratios to equal 1 (O/E = 1), thereby effectively making the annual number of adverse events predicted by the model match the annual number of adverse events observed in the entire registry; the differences between the calibrated and uncalibrated O/E ratios; and how and when to use each.

CHEST Watch: A High School Outreach Program.

As the US population ages, health care workforce shortages are projected in surgery, medicine, and nursing. We describe an outreach program aimed at exposing high school students to health care as a career choice while emphasizing science courses and prevention of tobacco use. High school students were invited to participate in CHEST Watch, a structured educational program based on thoracic pathology. Before students attended the program, parental consent was collected. Students engaged in a discussion with multiple professionals (physicians, nurses, smoking cessation counselors, social workers, basic science researchers) who presented their personal motivation and information about the corresponding career. Participants then observed a lung cancer surgery. A strong anti-tobacco message was emphasized throughout. Before and after the event, the participants completed anonymous opinion surveys which queried their interest in science, health care careers, and tobacco use. The Cochran-Mantel-Haenszel test was used for trend analysis. A total of 4400 students from 84 schools attended CHEST Watch over 15 years. A significant increase in the students' interest in health care careers and science courses (P-value 0.0001) and a significant decrease in tobacco use interest (P-value 0.0001) were observed. Overall, feedback was strongly positive and very popular within the school systems. The CHEST Watch program is an innovative approach intended to recruit youth into health care careers to address projected future shortages in the workforce. Furthermore, the participants' experience resulted in an increasingly positive attitude towards personal health and a decreased interest in use of tobacco products.

Post operative pediatric appendicitis nurse-driven discharge: Patient outcomes and nursing perspectives.

BACKGROUND: Nurse-driven discharge pathways following pediatric appendectomies have proven effective in children's hospitals; studies in general hospital settings are lacking. Additionally, despite the central role of nursing in such pathways, nursing perspectives aren't investigated in the literature. METHODS: Data from all pediatric acute uncomplicated appendicitis patients who underwent laparoscopic appendectomy in the 12 months following institution of a nurse-driven discharge pathway (intervention, n = 67) were compared to those treated in the preceding year (control, n = 64). Surveys on the pathway were distributed to pediatric ward nurses. RESULTS: Postoperative length of stay (POLOS) decreased by 37% in the intervention group, about 6 h, (0.44 days ± 0.22 vs 0.7 days ± 0.27, p-value 0.0001), without a significant increase in related readmissions. Same day discharges increased from 10.9% to 46.3%, (P-value 0.0001). Nurse surveys revealed a high approval of the pathway (7-10/10) and yielded valuable feedback. CONCLUSION: A nurse-driven discharge pathway decreased POLOS without increasing readmission following pediatric laparoscopic appendectomy in a general hospital setting. Valuable insight into nursing perspectives on this pathway was acquired.

Results of Lung Cancer Screening in the Community.

PURPOSE: To address doubts regarding National Lung Screening Trial (NLST) generalizability, we analyzed over 6,000 lung cancer screenings (LCSs) within a community health system. METHODS: Our LCS program included 10 sites, 7 hospitals (2 non-university tertiary care, 5 community) and 3 free-standing imaging centers. Primary care clinicians referred patients. Standard criteria determined eligibility. Dedicated radiologists interpreted all LCSs, assigning Lung Imaging Reporting and Data System (Lung-RADS) categories. All category 4 Lung-RADS scans underwent multidisciplinary review and management recommendations. Data was prospectively collected from November 2013 through December 2018 and retrospectively analyzed. RESULTS: Of 4,666 referrals, 1,264 individuals were excluded or declined, and 3,402 individuals underwent initial LCS. Second through eighth LCSs were performed on 2,758 patients, for a total of 6,161 LCSs. Intervention rate after LCS was 14.6% (500 individuals) and was most often additional imaging. Invasive interventions (n = 226) were performed, including 141 diagnostic procedures and 85 surgeries in 176 individuals (procedure rate 6.6%). Ninety-five lung cancers were diagnosed: 84 non-small cell (stage 1: 60; stage 2: 7; stage 3: 9; stage 4: 8), and 11 small cell lung cancers. The procedural adverse event rate was 23/226 (10.1%) in 21 patients (0.6% of all screened individuals). Pneumothorax (n = 10) was the most frequent, 6 requiring pleural drainage. There were 2 deaths among 85 surgeries or 2.3% surgical mortality. CONCLUSIONS: Our LCS experience in a community setting demonstrated lung cancer diagnosis, stage shift, intervention frequency, and adverse event rate similar to the NLST. This study confirms that LCS can be performed successfully, safely, and with equivalence to the NLST in a community health care setting.

Duodenal GI stromal tumors: Is radical resection necessary?

BACKGROUND AND OBJECTIVES: Duodenal gastrointestinal stromal tumors (GISTs) are rare tumors that pose a surgical challenge, and long-term outcomes after resection have not been detailed outside of small case series. This study uses the National Cancer Database (NCDB) to examine the determinants of radical resection for duodenal GISTs as well as the impact of local vs radical resection on overall survival (OS). METHODS: The NCDB was queried for nonmetastatic duodenal GISTs from 2004 to 2014. Predictors of radical resection were determined using multivariate logistic regression stratified by extent of tumor involvement. Factors associated with OS were identified with Cox proportional regression analysis. RESULTS: Treatment at an academic center, size >5 cm, and extra-duodenal extension were associated with radical resection. On multivariate analysis, radical resection was associated with decreased OS (HR, 1.93; P < .03). Systemic therapy, extra-duodenal extension, grade, stage, mitoses, and receipt of systemic therapy did not impact OS. CONCLUSION: Local resection of duodenal GISTs is associated with improved OS compared to radical resection after controlling for tumor factors and systemic treatment. Traditional indicators of tumor aggressiveness were associated with radical resection, but not OS. When feasible, local resection should be considered for resection of duodenal GISTs.

Early Weight Gain in Infants With Cleft Lip and Palate Treated With and Without Nasoalveolar Molding: A Retrospective Study.

OBJECTIVE: To assess weight gain of infants with cleft lip and/or palate (CL ± P) treated with nasoalveolar molding (NAM). DESIGN: Retrospective, case-control chart review. SETTING: Doernbecher Children's Hospital, Oregon Health & Science University, Portland, Oregon. PATIENTS, PARTICIPANTS: Infants with nonsyndromic CL ± P and noncleft controls. INTERVENTIONS: Prior to primary lip surgery, NAM was either included (+NAM) or not included (-NAM) in the cleft treatment protocol. MAIN OUTCOME MEASURE(S): Weight gain and percentage weight gain relative to initial weight were compared among +NAM, -NAM, and control groups from birth to 7 months and from birth to 36 months. RESULTS: Comparing +NAM and -NAM groups, no significant difference in weight or percentage weight gain was found in either time window. Compared to controls, from birth to 7 months, both CL ± P groups weighed less (P < .001), while percentage weight gain was greater for the +NAM (P < .001) and did not differ for -NAM. From birth to 36 months relative to controls, weight for +NAM showed no significant difference and -NAM weighed less (P < .01), while percentage weight gain was greater for both CL ± P groups (P < .001). CONCLUSIONS: Comparisons of CL ± P infants treated with and without NAM showed that with the NAM appliance, despite its added complexity, there was no adverse impact on weight gain. Comparisons to noncleft, control infants suggests that NAM treatment may have a beneficial impact on weight gain.

An In Vivo and Cone Beam Computed Tomography Investigation of the Accuracy in Measuring Alveolar Bone Height and Detecting Dehiscence and Fenestration Defects.

PURPOSE: To investigate cone beam computed tomography (CBCT) accuracy in measuring facial bone height and detecting dehiscence and fenestration defects around teeth. MATERIALS AND METHODS: Patients who were treatment planned for periodontal flap or dental implant surgeries were enrolled (n = 25). CBCT imaging (Carestream CS 9300) was obtained at 0.09-mm voxels (n = 10 patients, 23 teeth) and at 0.18-mm voxels (n = 15 patients, 33 teeth). Facial bone height measurements, from cusp tip to crest of bone height along the long axis of the tooth, and presence or absence of dehiscence or fenestration defects were recorded from CBCT images in triplicates independently by two examiners. The corresponding clinical measurements were made at the time of surgery. Comparisons of CBCT and clinical measurements were made using paired t tests for teeth: anterior and posterior, maxillary and mandibular, with or without restorations, or root canal therapy. Level of agreement between investigators was assessed by concordance correlation coefficients (CCC), Pearson's correlation coefficient (PCC), and Cohen's Kappa. RESULTS: Comparing mean CBCT and clinical measurements, statistically significant differences were noted for 0.09-mm and 0.18-mm voxel sizes, for anterior and posterior teeth, for maxillary and mandibular teeth, for teeth with or without restorations, and for teeth without root canal therapy (P < .05). Clinical and CBCT measurements were similar for teeth with crowns and with root canal therapy (P > .05). CBCT measurements underestimated mean facial bone height from 0.33 ± 0.78 to 0.88 ± 1.14 mm (mean ± SD) and absolute facial bone height values from 0.56 ± 0.35 to 1.08 ± 0.92 mm. Intraexaminer and interexaminer reliability for measuring facial bone height ranged from poor to substantial (PCC = 0.78 to 0.97 and CCC = 0.63 to 0.96, respectively). Interexaminer reliability for detection of dehiscence and fenestration defects ranged from poor to moderate (Cohen's Kappa = -0.09 to 0.66). CONCLUSION: CBCT imaging underestimated facial bone height and overestimated the presence of dehiscence and fenestration defects.

Regional Thoracic Surgery Quality Collaboration Formation: Providence Thoracic Surgery Initiative.

BACKGROUND: Surgery quality initiatives improve clinical outcomes in cardiac and general surgery. No mature thoracic surgery (TS) regional effort has been described. METHODS: An intramural grant funded the Thoracic Surgery Initiative (TSI). Professional organization, site-specific administrative and clinical databases were used to identify surgeons performing TS across a large Western health system. Participants were recruited through stakeholder surveys, personal contact, and meetings. Differences in practices and outcomes were identified. Fourteen centers performing TS in 5 states formed the TSI with a mission to define, implement, and monitor TS quality. RESULTS: A TS data system based on The Society of Thoracic Surgeons General Thoracic Surgery Database was implemented. Clinical data from 2015 and 2016 revealed significant differences in outcomes. Clinical data allow quality implementation, including identification and propagation of internal best practices and monitoring. TS practice standardization was agreed to using predefined TS best practice components that were incorporated into standardized TS care documents. Standardized care document completion by providers was intended to provoke desired TS care. The standardized care documents reside on the system-wide electronic health record. Literature and substantial surgeon experience were used to develop standardized TS care pathways for important or common clinical scenarios (pneumonectomy, primary spontaneous pneumothorax, etc). The TSI internet site serves as a harbor for standardization products. CONCLUSIONS: The TSI is evolving. Surgeon engagement remains high. The TSI enabled surgeons to lead, set the agenda, and remain in control of our destiny. Indeed, health care cannot appropriately evolve without such physician vision, engagement, and leadership.

Accuracy and Reproducibility of Radiographic Images for Assessing Crestal Bone Height of Implants Using the Precision Implant X-ray Locator (PIXRL) Device.

PURPOSE: Assessment of crestal bone levels around implants is essential to monitor success and health. This is best accomplished with intraoral radiographs exposed at 90 degrees to the long axis of the implant, but this can be challenging to achieve clinically. Radiographic paralleling devices produce orthogonal radiographs but traditionally have required access to the implant body for each exposure. This study was conducted to determine if use of the Precision Implant X-ray Locator (PIXRL), a radiographic paralleling device that indexes the implant at the time of surgical placement, can produce orthogonal radiographs of dental implants more accurately than traditional radiologic techniques for assessing crestal bone levels. MATERIALS AND METHODS: Three dental implants were inserted in dry human skulls in supracrestal positions to simulate crestal bone loss (maxillary right first premolar [site 14], maxillary right central incisor [site 11], and mandibular left second premolar [site 35]). The implants were masked with a soft tissue moulage and restored with provisional restorations. Four dental assistants exposed six radiographs using their usual and customary technique and six using the PIXRL device for each implant. A single examiner measured crestal bone levels on the radiographs relative to the implant platform shoulder on the mesial and distal of each implant. Recorded measurements were compared to the known values. Statistical analysis was completed using a generalized linear regression model to analyze the differences, and post-hoc comparisons with pairwise adjustment were applied. RESULTS: The images produced using the PIXRL device were more accurate overall compared to traditional techniques and were also more consistent. The greater degree of accuracy was statistically significant for all sites with the exception of the mesial measurements of the implant at site 11. CONCLUSION: This study demonstrates that the use of the PIXRL device can assist clinicians in obtaining more accurate orthogonal radiographs for assessing crestal bone height and would be a useful tool for researchers utilizing radiographic imaging of implants as a longitudinal measure of implant success and stability.

Bioprosthetic Aortic Valve Durability: A Meta-Regression of Published Studies.

To compare structural valve deterioration (SVD) among bioprosthetic aortic valve types, a PubMed search found 54 papers containing SVD-free curves extending to at least 10 years. The curves were digitized and fit to Weibull distributions, and the mean times to valve failure (MTTF) were calculated. Twelve valve models were collapsed into four valve types: Medtronic (Medtronic, Minneapolis, MN) and Edwards (Edwards Lifesciences, Irvine, CA) porcine; and Sorin (Sorin Group [now LivaNova], London, United Kingdom) and Edwards pericardial. Meta-regression found MTTF was associated with the patient's age, publication year, SVD definition, and valve type. Sorin pericardial valves had significantly lower risk-adjusted MTTF (higher SVD risk), and there were no significant differences in MTTF among the other three valve types.

CHADS2 Score Predicts Postoperative Atrial Fibrillation in Patients Undergoing Elective Pulmonary Lobectomy.

BACKGROUND: Postoperative atrial fibrillation (PAF) affects 12% to 17% of patients undergoing lobectomy and is associated with increased morbidity. CHADS2 (congestive heart failure history, hypertension history, age ≥75 years, diabetes mellitus history, and stroke or transient ischemic attack symptoms previously) is used to predict stroke risk in patients with existing AF. It also has been shown also to predict new-onset PAF. Our objective was to determine whether CHADS2 can predict PAF in patients undergoing lobectomy. METHODS: A prospective thoracic surgery clinical database was reviewed to identify adult patients, without prior AF, who underwent elective lobectomy between January 1, 2005, and June 30, 2014. Nonelective and combined operations were excluded. Two groups (PAF and no PAF) were analyzed. RESULTS: PAF developed in 113 of 933 patients with overall incidence of 12% for the entire group. Age (≥75 years) and coronary artery disease were the only significant preoperative characteristics between the two groups. Intensive care unit readmission, new neurologic events, length of stay, 30-day survival, and hospital mortality were significantly higher in the PAF group as were mean CHADS2 scores (1.4 and 1.1 respectively, p = 0.0014). Incidence of PAF ranged from 7.9% in low-risk groups to 11% in moderate-risk and 17.7% in high-risk groups, which was also significant, p < 0.0002. Similar findings were noted for CHA2DS2-VASc (age in years, sex, history of congestive heart failure, history of hypertension, history of stroke/transient ischemic symptoms/thromboembolic events, history of vascular disease, history of diabetes mellitus). CONCLUSIONS: Although multiple risk factors for PAF have been described, no easily applicable clinical model exists. Observed rate of PAF was significantly lower then the previously described 12% when CHADS2 was 0. CHADS2 can predict PAF in patients undergoing elective lobectomy and can identify patients to selectively institute prophylactic measures in patients at the greatest risk, such as patients with score of 2 or greater. Further validation of this model is warranted in a larger group.

Risk factors associated with calcium oxalate urolithiasis in dogs evaluated at general care veterinary hospitals in the United States.

Calcium oxalate urolithiasis results from the formation of aggregates of calcium salts in the urinary tract. Difficulties associated with effectively treating calcium oxalate urolithiasis and the proportional increase in the prevalence of calcium oxalate uroliths relative to other urolith types over the last 2 decades has increased the concern of clinicians about this disease. To determine factors associated with the development of calcium oxalate urolithiasis in dogs evaluated at general care veterinary hospitals in the United States, a retrospective case-control study was performed. A national electronic database of medical records of all dogs evaluated between October 1, 2007 and December 31, 2010 at 787 general care veterinary hospitals in the United States was reviewed. Dogs were selected as cases at the first-time diagnosis of a laboratory-confirmed urolith comprised of at least 70% calcium oxalate (n=452). Two sets of control dogs with no history of urolithiasis diagnosis were randomly selected after the medical records of all remaining dogs were reviewed: urinalysis examination was a requirement in the selection of one set (n=1808) but was not required in the other set (n=1808). Historical information extracted included urolith composition, dog's diet, age, sex, neuter status, breed size category, hospital location, date of diagnosis, and urinalysis results. Multivariable analysis showed that the odds of first-time diagnosis of calcium oxalate urolithiasis were significantly (P<0.05) greater for dogs<7 years, males (OR: 7.77, 95% CI: 4.93-12.26), neutered (OR: 2.58, 1.44-4.63), toy- vs. medium-sized breeds (OR: 3.15, 1.90-5.22), small- vs. medium-sized breeds (OR: 3.05, 1.83-5.08), large- vs. medium-sized breeds (OR: 0.05, 0.01-0.19), and those with a diagnosis of cystitis within the previous year (OR: 6.49, 4.14-10.16). Urinary factors significantly associated with first-time diagnosis of calcium oxalate urolithiasis were acidic vs. basic pH (OR: 1.94, 1.22-3.10), presence of RBCs (OR: 6.20, 3.91-9.83) or WBCs (OR: 1.62, 1.03-2.54), and protein concentration>30 mg/dL (OR: 1.55, 1.04-2.30). Patient demographics and urinalysis results are important factors that can support risk assessment and early identification of canine oxalate urolithiasis. Therefore, periodic urolith screening and monitoring of urine parameters should be encouraged for dogs at risk of developing these uroliths.

Risk factors associated with the development of chronic kidney disease in cats evaluated at primary care veterinary hospitals.

OBJECTIVE: To identify risk factors associated with diagnosis of chronic kidney disease (CKD) in cats. DESIGN: Retrospective case-control study. ANIMALS: 1,230 cats with a clinical diagnosis of CKD, serum creatinine concentration > 1.6 mg/dL, and urine specific gravity < 1.035 and 1,230 age-matched control cats. PROCEDURES: Data on putative risk factors for CKD were extracted for multivariate logistic regression analysis from the medical records of cats brought to 755 primary care veterinary hospitals. For a subset of cats evaluated 6 to 12 months prior to the date of CKD diagnosis or control group inclusion, the percentage change in body weight between those dates as well as clinical signs at the earlier date were analyzed for associations with CKD development. RESULTS: Risk factors for CKD in cats included thin body condition, prior periodontal disease or cystitis, anesthesia or documented dehydration in the preceding year, being a neutered male (vs spayed female), and living anywhere in the United States other than the northeast. The probability of CKD decreased with increasing body weight in nondehydrated cats, domestic shorthair breed, and prior diagnosis of diabetes mellitus and increased when vomiting, polyuria or polydipsia, appetite or energy loss, or halitosis was present at the time of diagnosis or control group inclusion but not when those signs were reported 6 to 12 months earlier. Median weight loss during the preceding 6 to 12 months was 10.8% and 2.1% in cats with and without CKD, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The probability of CKD diagnosis in cats was influenced by several variables; recent weight loss, particularly in combination with the other factors, warrants assessment of cats for CKD.

A moderate fat, low-energy dry expanded diet reduces gain in body condition score when fed as part of a post neutering weight-control regimen in growing pet cats.

Neutering of cats has been associated with significant weight gain in the weeks following surgery. The present study aimed to evaluate the effectiveness of a moderate fat, low-energy dry expanded diet in reducing weight gain in growing pet cats when fed as part of a weight-control regimen over the 6 months post-neutering. Cats in participating primary care veterinary hospitals were enrolled at neutering and assigned to receive one of the two dietary treatments based on the hospital of origin. Owners of cats in the treatment group were instructed to feed the trial diet at maintenance (324·7 kJ/kg BW(0·711) per d). Instructions for the control group were to feed the cat's regular diet according to the manufacturer's recommendations. Body weight and condition were evaluated by veterinarians at enrolment, 2-weeks, and 1-4 and 6 months after surgery. Body condition score (five-point scale) was compared between enrolment and each subsequent visit, controlling for enrolment age and sex. Percentage change in body weight was evaluated via multivariate mixed modelling to account for repeated measures. A total of 187 cats (eighty-seven females and 100 males) with a mean age of 5·2 (sd 0·8) months and mean weight of 2·8 (sd 0·6) kg from fifty-one hospitals completed the trial. The odds of being scored as overweight were 4·1 times as great for cats in the control v. treatment groups (95 % CI 2·1, 8·2). Percentage change in body weight differed significantly with enrolment age (P = 0·007) and approached significance between diet groups (P = 0·08). Cats fed the trial diet had a significantly reduced incidence of overweight in the 6 months following neutering.