Description of Socio demographic and Pre-operative Factors
Out of a total of 385 adult patients, 368 included in the analysis (17 patients excluded due to incomplete documents and refusal) with response rate of 95%. Of the total patients included in the analysis, 55.7 % were female and 44.3 % were male. The ages ranged from 20 to 88 years. Most of the patients (44%) were aged between 20 and 30 years. The body mass index (BMI) was obtained by dividing weight (in kilograms) over square of the height (in meters). Forty (10.9%) of the study patients were obese with a BMI of over 30. (Table 1).
Table :1 Summary of description of pre-operative factors among surgical elective patients at JUMC, from August 1, 2019 to September 30, 2019
Variables
|
Frequency
|
Percentages
|
Sex of patient
|
Male
|
163
|
44.3
|
Female
|
205
|
55.7
|
Age of patient
|
20 – 30
|
162
|
44
|
31 – 40
|
129
|
35.1
|
41 – 50
|
45
|
12.2
|
>50
|
32
|
8.7
|
BMI of the patient
|
<20 (underweight)
|
44
|
12.0
|
20 - 25 (normal weight)
|
224
|
60.9
|
26 - 30 (overweight)
|
60
|
16.3
|
>30 (obese)
|
40
|
10.9
|
(BMI = Body mass index, PONV = Post-operative nausea and vomiting)
Peri-Operative Factors that are candidate for final mode
Output of binary logistic regression analysis identifies the following pre-operative factors as potential candidate for final model (with p value < 0.25): Female gender, age, previous history of PONV and migraine headache, BMI and non administration of anti emetic prophylaxis (Table 2)
Table 2: Results of binary logistic regression analysis showing pre-operative factors that are candidate for final analysis model among surgical elective patients at JMC, from August 1, 2019 to September 30, 2019
Variables
|
Incidence of PONV
|
COR (95% CI)
|
P-value
|
Present (%)
|
Absent (%)
|
Sex
|
Male
|
18 (11.0)
|
145 (89.0)
|
1
|
|
Female
|
83 (40.5)
|
122 (59.5)
|
5.480 (3.119 – 9.629) *
|
0.000
|
Age
|
20 – 30
|
38 (23.5)
|
124 (76.5)
|
0.448 (0.203-0.990) *
|
0.047
|
31 – 40
|
30 (23.3)
|
99 (76.7)
|
0.443 (0.196-1.001)
|
0.050
|
41 – 50
|
20 (44.4)
|
25 (55.6)
|
1.169 (0.467-2.929)
|
0.739
|
>50
|
13 (40.6)
|
19 (59.4)
|
1
|
|
BMI
of the patient
|
< 20
|
7 (15.9)
|
37 (84.1)
|
1
|
|
20 - 25
|
59 (26.3)
|
165 (73.7)
|
1.890 (0.799 - 4.470)
|
0.147
|
26 - 30
|
19 (31.7)
|
41 (68.3)
|
2.449 (0.925 - 6.487)
|
0.071
|
>30
|
16 (40.0)
|
24 (60.0)
|
3.524 (1.263 - 9.831) *
|
0.016
|
Previous history
of PONV
|
Yes
|
57 (42.9)
|
76 (57.1)
|
3.256 (2.025-5.234) *
|
0.000
|
No
|
44 (18.7)
|
191 (81.3)
|
1
|
|
Smoking history
|
Smoker
|
12 (32.4)
|
25 (67.8)
|
1
|
|
Non smoker
|
89 (26.9)
|
242 (73.1)
|
0.766 (0.369 – 1.590)*
|
0.024
|
Previous history of migraine headache
|
Yes
|
56 (31.8)
|
120 (68.2)
|
1.524 (0.962 – 2.416) *
|
0.073
|
No
|
45 (23.4)
|
147 (76.6)
|
1
|
|
Administration of antiemetic prophylaxis
|
Yes
|
12 (14.0)
|
74 (86.0)
|
1
|
|
No
|
89 (31.6)
|
193 (68.4)
|
2.844 (1.470-5.500) *
|
0.002
|
Presence of anxiety
|
Yes
|
35 (34.0)
|
68 (66.0)
|
1.552 (0.947 – 2.543) *
|
0.810
|
No
|
66 (24.9)
|
199 (75.1)
|
1
|
|
(PONV – Post-operative nausea and vomiting, 1 - Reference category, COR – Crude Odds Ratio, CI - Confidence Interval, * - significantly associated variables that are candidate for final analysis model at P value less than 0.25
Intra-operative factors that were potential candidate for final model
Intra-operative factors that were potential candidate for final model (with p value < 0.25) after binary logistic regression analysis included type of anesthesia used, use of intra-operative opioids, type of surgery, duration of anesthesia, administration of neostigmine and incidence of intraoperative hypotension. Conversely, type of induction and maintenance agents were not candidate for final model after binary logistic regression analysis(Table 3).
Table 3: Results of binary logistic regression analysis showing intra-operative factors that are candidate for final analysis model among surgical elective patients at JMC, from August 1, 2019 to September 30, 2019
Variables
|
Incidence of PONV
|
COR (95% CI)
|
P- vale
|
Present (%)
|
Absent (%)
|
Types of anesthesia used
|
GA with ETT
|
59 (35.5)
|
107 (64.5)
|
0.551 (0.240-1.267)
|
0.161
|
GA sedation
|
6 (16.7)
|
30 (83.3)
|
0.200 (0.062-0.642) *
|
0.007
|
SA
|
23 (16.4)
|
117 (83.6)
|
0.197 (0.081-0.478) *
|
0.000
|
GA and SA
|
13 (50.0)
|
13 (50.0)
|
1
|
|
Type of induction agent for GA
|
Ketamine
|
38 (39.6)
|
58 (60.4)
|
1
|
|
Thiopentone
|
14 (34.1)
|
27 (65.9)
|
0.791 (0.369 -1.699)
|
0.618
|
Propofol
|
20 (26.3)
|
56 (73.7)
|
0.545 (0.283 -1.049)
|
0.952
|
Combination
|
6 (33.3)
|
12 (66.7)
|
0.763 (0.264 -2.207)
|
0.551
|
Agent for maintenance
|
Inhal. agents
|
60 (33.0)
|
122 (67.0)
|
1.059 (0.512 – 2.191)
|
0.877
|
IV agents
|
13 (31.7)
|
28 (68.3)
|
1
|
|
Intraoperative opioids
|
Used
|
75 (34.6)
|
142 (65.4)
|
2.336 (1.404-3.888) *
|
0.001
|
Not used
|
26 (18.4)
|
115 (81.6)
|
1
|
|
Use of neostigmine
|
Used
|
53 (39.0)
|
83 (61.0)
|
2.554 (1.585 – 4.117) *
|
0.000
|
Not used
|
44 (20.0)
|
176 (80.0)
|
1
|
|
Intraoperative hypotension
|
Present
|
18 (43.9)
|
23 (56.1)
|
2.301 (1.183 – 4.474) *
|
0.014
|
Not present
|
83 (25.4)
|
244 (74.6)
|
1
|
|
Type of surgery performed
|
Thyroid
|
4 (20.0)
|
16 (80.0)
|
1.750 (0.384 -7.969)
|
0.469
|
Gynecological
|
68(46.3)
|
79(53.7)
|
6.025 (2.012 - 8.041) *
|
0.001
|
Abdominal
|
5 (20.8)
|
19 (79.2)
|
1.842 (0.437 - 7.760)
|
0.405
|
Orthopedic
|
7 (8.3)
|
77 (91.7)
|
0.636 (0.173 - 2.341)
|
0.496
|
Plastic
|
3 (13.0)
|
20 (87.0)
|
1.050 (0.211 - 5.217)
|
0.952
|
Maxillofacial
|
3 (11.1)
|
24 (88.9)
|
0.875 (0.178 - 4.307)
|
0.870
|
Urologic
|
4 (12.5)
|
28 (87.5)
|
1
|
|
Duration of anesthesia
|
≤ 60 min
|
20 (14.7)
|
116 (85.3)
|
1
|
|
> 60 min
|
81 (34.4)
|
151 (65.1)
|
3.111 (1.802 – 5.371) *
|
0.000
|
(PONV – Post-operative nausea and vomiting, 1 - Reference category, COR – Crude Odds Ratio, CI - Confidence Interval, GA – General anesthesia, SA – Spinal anesthesia, IV – intravenous anesthesia, ETT – Endotracheal intubation, * - significantly associated variables that are candidate for final analysis model at P value less than 0.25)
Post-operative factors that were potential candidate for final model
Post-operative factors such as, administration of post-operative opioid and severity of post-operative pain were identified as potential candidate for multiple logistic regression. However, time of first oral intake was not candidate for final model (Table 4)
Table 4: Results of binary logistic regression analysis showing post-operative factors that are candidate for final analysis model among surgical elective patients at JMC, from August 1, 2019 to September 30, 2019
Variables
|
Incidence of PONV
|
COR (95% CI)
|
P-value
|
Present (%)
|
Absent (%)
|
Timing of first oral intake after operation
|
0 – 6
|
6 (27.3)
|
16 (72.7)
|
1
|
|
7 – 12
|
8 (15.4)
|
44 (84.6)
|
0.485 (0.146 - 1.615)
|
0.288
|
13 – 24
|
53 (27.6)
|
139 (72.4)
|
1.017 (0.378 - 2.737)
|
0.974
|
>24
|
34 (33.3)
|
68 (66.7)
|
1.333 (0.479 - 3.715)
|
0.583
|
Severity of post-operative pain
|
Less pain
|
32 (19.2)
|
135 (80.8)
|
1
|
|
More pain
|
69 (34.3)
|
132 (65.7)
|
2.205 (1.361 - 3.575) *
|
0.001
|
Post-operative use of opioids
|
Used
|
77 (37.7)
|
127 (62.3)
|
3.537 (2.108 – 5.933 *
|
|
Not used
|
24 (14.6)
|
140 (85.4)
|
1
|
0.000
|
(PONV – Post-operative nausea and vomiting, 1 - Reference category, COR – Crude Odds Ratio, CI - Confidence Interval, * - significantly associated variables that are candidate for final analysis model at P value less than 0.25)
5.5 Independent Predictors of PONV
Risk factors associatedwith PONV were analyzed further. All factors that turned out with a significant level (p value < 0.25) on after binary logistic regression analysis were used to model for final analysis. Consequently, backward multiple logistic regression analysis was used to determine the association of perioperative factors with the incidence of PONV. Accordingly, output of multiple logistic regression model revealed that sex, history of PONV or motion sickness, long duration of anaesthesia, Gynecological type of surgery and administration of post-operative opioids as independent predictors of PONV at significant level (p < 0.05).
Female patients was identified as strongest pre-operative independent predictor with (AOR = 4.065, CI = 2.090 - 7.906). Whereas, previous history of PONV or motion sickness was also one of independent predictor of PONV with (AOR = 2.836, CI = 1.582 - 5.083). Among intra-operative factors, only duration of anesthesia greater than sixty minutes (AOR = 2.974, CI = 1.491 - 5.933) and Gynecologic type of surgery (AOR = 3.782, CI = 1.156 - 12.373) were identified as independent predictor. Whereas, only post-operative opioids administration (AOR = 2.333, CI = 1.221 - 4.457) was identified as independent factors among post-operative factors (Table 5)
Table 5: Output of multiple logistic regression analysis model showing independent predictors of PONV among surgical elective patients at JMC, from August 1, 2019 to September 30, 2019
Variables
|
Incidence of PONV
|
AOR (95% CI)
|
P-value
|
Present (%)
|
Absent (%)
|
Sex
|
Male
|
18 (11.0)
|
145 (89.0)
|
1
|
|
Female
|
83(40.5)
|
122 (59.5)
|
4.065 (2.090 - 7.906) *
|
0.000
|
History of PONV
|
Yes
|
57 (42.9)
|
76 (57.1)
|
2.836 (1.582 - 5.083) *
|
0.000
|
No
|
44 (18.7)
|
191 (81.3)
|
1
|
|
Duration of Anesthesia
|
≤ 60 min
|
20 (14.7)
|
116 (85.3)
|
1
|
0.002
|
> 60 min
|
81 (34.4)
|
151 (65.1)
|
3.089 (1.467 – 6.505) *
|
|
Post-operative opioids
|
Used
|
77 (37.7)
|
127 (62.3)
|
2.333 (1.221 - 4.457) *
|
0.010
|
Not used
|
24 (14.6)
|
140 (85.4)
|
1
|
|
Type of surgery performed
|
Thyroid
|
4 (20.0)
|
16 (80.0)
|
0.835 (0.161 - 4.323)
|
|
Gynecology
gical
|
68 (46.3)
|
79 (53.7)
|
3.782(1.156 - 12.373) *
|
0.028
|
Abdominal
|
5 (20.8)
|
19 (79.2)
|
3.133 (0.632 - 15.531)
|
|
Orthopedic
|
7 (8.3)
|
77 (91.7)
|
0 .460 (0.114 - 1.859)
|
|
Plastic
|
3 (13.0)
|
20 (87.0)
|
1.677 (0.298 - 9.423)
|
|
Maxillofacial
|
3 (11.1)
|
24 (88.9)
|
0 .688 (0.125 - 3.789)
|
|
Urologic
|
4 (12.5)
|
28 (87.5)
|
1
|
|
(PONV – Post-operative nausea and vomiting, 1 - Reference category, AOR – Adjusted Odds Ratio, COR – Crude Odds Ratio CI - Confidence Interval, * - independent predictors of PONV at P value less than 0.05)