Stomatitis

Cost estimation for a pathology treated with any drug is made by identification of the resources used in the process, measuring and quantifying these resources and assigning a standard price to each of these resources (in monetary units).
Usually, in this type of pharmacoeconomic analysis, only direct medical costs are included, without taking into account indirect and intangibles costs.
Three main categories of costs, derived from routine clinical practice in the Spanish hospitals, were considered in the cost-minimisation analysis:

costs of the study drug;

costs of drug administration (e.g. cost of outpatient visits, infusions);

costs of managing adverse events (e.g. cost of additional medication, any associated hospitalisation).

To estimate the costs derived from each arm of the trial, the total amount of study drug per patient, used during the clinical trial, was calculated by multiplying each dose (mg m⁻²) administered by the patient's surface area and summing overall doses administered. The result was then multiplied by the cost of the study drug. The cost for outpatient consultations (at the beginning of each treatment cycle) and outpatient visits (for administration of each dose) were also added. In each administration of T, the use of antiemetic drugs (granisetron and tropisetron, in 66.7 and 33.3% of patients, respectively, according to expert opinion) was also required. Table 1Table 1

	Total mg drug used	Mg per patient	Total cycles	Cycles per patient	Total doses
PLD
(n=239)	94 447	395.18	1164	4.87	1164
Topotecan
(n=235)	15 653	66.60	1349	5.74	6673

PLD=pegylated liposomal doxorubicin hydrochloride.

shows the amounts of study drug and cycles (total and per patient) used to make these estimations (Gordon et al, 2001 (link); Smith et al, 2002 (link)).
The resources used to manage every adverse event were measured for each drug, PLD and T. First, frequency of adverse events by type and severity level for both drugs was analysed, as shown in Table 2Table 2

Adverse event type	Grade	PLD n (%)	Topotecan n (%)
Anemia	Total	319 (100)	985 (100)
	Grade I	199 (62)	363 (37)
	Grade II	101 (32)	476 (48)
	Grade III	18 (6)	134 (14)
	Grade IV	1 (0)	12 (1)
Thrombocytopenia	Total	71 (100)	944 (100)
	Grade I	54 (76)	434 (46)
	Grade II	14 (20)	272 (29)
	Grade III	3 (4)	175 (19)
	Grade IV	0 (0)	63 (7)
Neutropenia	Total	311 (100)	1438 (100)
	Grade I	153 (48)	296 (20)
	Grade II	105 (35)	378 (26)
	Grade III	42 (14)	427 (30)
	Grade IV	11 (3)	337 (24)
Sepsis	Total	4 (100)	17 (100)
	Grade I	0 (0)	0 (0)
	Grade II	1 (25)	5 (35)
	Grade III	3 (75)	3 (15)
	Grade IV	0 (0)	9 (50)
Fever	Total	69 (100)	65 (100)
	Grade I	36 (55)	31 (48)
	Grade II	26 (42)	20 (31)
	Grade III	2 (3)	8 (12)
	Grade IV	0 (0)	5 (9)
Stomatitis/Pharyngitis	Total	378 (100)	130 (100)
	Grade I	202 (53)	91 (70)
	Grade II	144 (38)	37 (28)
	Grade III	31 (8)	2 (2)
	Grade IV	1 (0)	0 (0)
Nausea/Vomiting	Total	386 (100)	567 (100)
	Grade I	236 (61)	333 (59)
	Grade II	110 (28)	175 (31)
	Grade III	37 (10)	51 (9)
	Grade IV	3 (1)	8 (1)
Diarrhoea	Total	74 (100)	126 (100)
	Grade I	42 (57)	68 (54)
	Grade II	26 (35)	47 (37)
	Grade III	5 (7)	10 (8)
	Grade IV	1 (1)	1 (1)
PPE	Total	379 (100)	2 (100)
	Grade I	195 (51)	2 (100)
	Grade II	120 (32)	0 (0)
	Grade III	62 (16)	0 (0)
	Grade IV	2 (1)	0 (0)

PLD=pegylated liposomal doxorubicin hydrochloride; PPE=palmar-plantar erythrodysesthesia.

(Gordon et al, 2001 (link); Smith et al, 2002 (link)). Then, the costs derived from the treatment of each type of adverse event in each of their severity levels were determined. These results were used to calculate the cost per adverse event and per patient. The estimated cost for each adverse event type was then added to obtain a total adverse event management cost per patient.

A convenience sample of 108 dogs presented for dental care under general anesthesia including complete oral examination and radiographs was recruited from 3 veterinary clinics that consented to participate in the study. These included one referral specialty dental practice (n = 57), one general small animal practice with a focus on veterinary dentistry (n = 29), and the community practice of a veterinary teaching hospital (n = 22). Five veterinarians performed the anesthetic procedures and radiographic assessments.
Dogs likely to show aggression were excluded from enrollment in the study. Prior to sedation, an investigator with previous experience in general veterinary practice performed a VA of each dog’s mouth. The lips and cheeks were retracted to allow the labial and buccal surfaces of the teeth and gingival margins to be examined with a focus on the gingival margins. The mouth was opened slightly to allow examination of the mandibular teeth and gingiva. A full mouth grade of PD between 0 and IV based on the tooth with the greatest level of pathologic change was recorded for each dog. The scoring system was derived from that of the AVDC [19 ]. As illustrated in Table 1, the scale utilized by the investigator(s) did not include the radiographic definitions for each stage of PD. For a subset of the dogs, a second investigator independently evaluated the dog’s teeth at the same visit and recorded the grade of PD in order to determine IRR. After the dental procedure was performed under general anesthesia, the attending veterinarian’s grade for PD was recorded based upon the tooth/teeth with the greatest level of pathology as detected by examination (including periodontal probing for measurement of the degree of gingival recession and attachment loss) and radiography as illustrated in Table 2. Information was also collected on the sex, neuter status, breed, and age of each dog (S1 Appendix).
As listed in the S1 Appendix, a total of 108 dogs were initially enrolled in the study. Informed consent was obtained from the caretaker of each dog enrolled in the study. All experimental procedures were approved by the Clinical Review Panel of the Purdue University College of Veterinary Medicine and the Purdue University Animal Care and Use Committee.
Of the 108 dogs initially enrolled in the study, 11 (10.18%) did not undergo the planned anesthetic procedure, 2 (1.85%) had a diagnosis that was not PD (1 stomatitis, 1 neoplasia), and 6 (5.56%) did not have dental radiography performed. This resulted in a sample of 89 dogs for analysis of agreement with RS (Table 3). The sample included 66 purebred dogs representing 37 breeds along with 21 mixed breed dogs and 2 dogs without breed identified. Mean age was 7.85 years and ranged from 1 to 14 years. Forty-seven dogs were male (41 neutered, 6 intact), and 42 were female (39 spayed, 3 intact).
Fifty-nine dogs (including 7 dogs that did not complete the anesthetic dental procedure, 1 dog with a diagnosis of neoplasia, and 3 dogs that did not have radiographs taken and were thus not included in the RS portion of the study) were evaluated by both of the raters. The sample population consisted of 41 purebred dogs representing 31 different breeds along with 11 mixed breed dogs. Mean age was 7.56 years ranging from 1 to 14 years. Twenty-seven dogs were male (21 neutered, 6 intact) and 32 dogs were female (30 spayed, 2 intact).

Reference was made to published studies; four common and important DNA viruses were used to evaluate the specificity of the RAA assay [10 (link),50 (link)]. The five viruses are goat pox virus, sheep pox virus, African swine fever virus, bovine papular stomatitis virus and pseudorabies virus. African swine fever virus is stored in Biosafety Laboratory Level 3, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences. Viral RNA of the four viruses was extracted as a template to evaluate the specificity of the RAA assay.

Eight Standardbred mares aged from 9 to 21 years (mean ± SD, 16 ± 4.93 years) and nine Amiata donkey jennies aged from 7 to 15 years (mean ± SD, 12.36 ± 2.5 years) were included in the study. All animals were healthy, with body condition scores between 3–4 out of 5 [25 (link)], cyclic, and had a history of normal fertility. Mares and jennies were kept in paddocks. Mares were fed mixed-grass hay and water ad libitum, and the diet was supplemented once a day with commercial horse feed (moisture content 12.2%, protein 16.3%, oils and lipids 1.7%, cellulose 6.8%, ash 2.7%, sodium 75 mg/kg; Equifioc, Molitoria Val di Serchio). Jennies were fed mixed-grass hay twice a day and water ad libitum. Quality details of the hay cannot be provided, but none of the animals were affected by contextual pathologies such as stomatitis, dysphagia, or FFWS linked to the poor quality of the hay, suggesting the adequacy of the provided hay [26 (link)]. Animals are checked weekly and body condition scores of both mares and jennies were monitored once a month and did not change during the study.

For each event of interest, we estimated the relative risk (RR) as a ratio of the proportions of the outcome in the control and cancer patients, and the hazard ratio (HR) was also calculated using the Cox proportional hazard regression method [18 ].
The proportional hazard assumption was explored by a log-minus-log plot. When the assumption was considered invalid, intervals for varying HRs were determined based on clinical advice and the exploration of the log-minus-log curves for any significant points of intersection.
A time-dependent HR of each treatment event was generated by applying a subdistribution hazard model with time-varying covariates [19 (link)], which is an extended Cox model accounting for time-varying covariates as well as time-independent covariates, considering death as a competing risk for the outcomes of treatment events. The subdistribution hazard ratio (SHR) was estimated at each defined interval and 95% confidence intervals (CIs) were computed.
Baseline diseases were considered as covariates for adjustment, and they primarily included diabetes, hypertension, hyperlipidemia, arthritis, osteoporosis, infectious disease, gastrointestinal disease, cardiovascular disease, and cerebrovascular disease. The baseline diseases were defined operationally as cases in which two or more disease-related codes were found within a year prior to the follow-up period. For diabetes, hypertension, and hyperlipidemia, cases where a disease-related code and at least one record of relevant medication prescribed for the disease were found were also included as indicators of baseline disease. A history of any dental disease of interest (i.e., stomatitis, tooth loss, dental caries/pulp disease, and gingivitis/periodontal disease) within a year prior to beginning of the follow-up period were also considered as a baseline disease covariate for adjustment (see Additional file 1: Table S2).
A subgroup analysis was performed by type of cancer in consideration of the cancer treatment site (oral cancer, other head and neck cancer, thyroid cancer, other solid cancer, and blood cancer) (see Additional file 1: Table S3).
All statistical analyses were performed using R version 3.3.3 [20 ] and SAS Enterprise Guide software (version 7.1; Copyright © 2003 SAS Institute Inc., Cary, NC, USA).