Associations between treatments and response to treatments from a large multicentre study of equine sinonasal disease

BACKGROUND: No large study has examined the treatment and response to treatment of horses with sinonasal disease confirmed by computed tomography (CT). OBJECTIVES: To report the treatment and response to treatment of referred cases of equine sinonasal disease. To explore associations between case outcome and clinical and endoscopic features, CT findings, disease subtypes, and treatments in a multivariable model. STUDY DESIGN: Retrospective case series. METHODS: Data were collected from medical records from 19 equine hospitals on cases of sinonasal disease, all of which underwent CT imaging. Case outcome was obtained from clinical records, and/or by contacting clients and referring veterinarians. Logistic regression analysis was used to examine associations between treatments and outcome and to identify associations between clinical and imaging variables and case outcome. RESULTS: Sinoscopic debridement with maxillary septal bulla fenestration was performed in 615/1299 (47.3%, 95% CI 44.6-50.1) horses where information on this parameter was available. Nasofrontal and maxillary sinusotomies were performed in 324/1302 (24.9%, 95% CI 22.6-27.3) and 93/1299 (7.2%, 95% CI 5.8-8.7) horses, respectively. Sinoscopic lavage was performed in 711/1299 (54.7%, 95% CI 52.0-57.4) cases, usually following other procedures. Sinoscopic treatment was associated with a higher likelihood of cure, and nasofrontal sinusotomy with a lower likelihood of cure, but difficult cases may have had more sinus osteotomies. Primary, dental and mycotic sinusitis had the highest complete cure rate (all over 79%), while sinonasal neoplasia (7.3%) and PEH (40.4%) had the lowest cure rates. Oral extraction OR 2.43 (95% CI 1.67-3.54, p < 0.001) and sinoscopic treatment OR 1.68 (95% CI 1.19-2.36, p = 0.003), were associated with increased likelihood of cure while cases treated by nasofrontal osteotomy were less likely to achieve cure OR 0.62 (95% CI 0.42-0.89, p = 0.011). Variables retained in the final multivariable model of clinical and endoscopic features, CT findings, disease sub-types and treatments, as significantly associated with cure that included 750 cases were: Final diagnoses of: Progressive ethmoid haematomas (OR 0.17, 95% CI 0.08-0.37, p < 0.001), sinonasal tumours (OR 0.02, 95% CI 0.00-0.06, p < 0.001) or Dental sinusitis (OR 0.38, 95% CI 0.19-0.76, p = 0.006) all having lower likelihood of cure than primary sinusitis. Cases that had undergone oral extractions were significantly more likely to be cured than those that did not (OR 3.1, 95% CI 1.66-5.81, p < 0.001). Cases treated by nasofrontal osteotomy were less likely to achieve cure (OR 0.38, 95% CI 0.24-0.61, p = 0.001) than those treated by other methods. Cases with bone hyperostosis graded as 'moderate or severe' were less likely to be cured than those with 'none or mild' (OR 0.54, 95% CI 0.35-0.82, p = 0.004). MAIN LIMITATIONS: Retrospective study with incomplete data for some cases. CONCLUSIONS: Oral extraction and sinoscopic treatments were associated with the highest likelihood of complete cure.