The Impact of Obstructive Sleep Apnea on Clinical, Perioperative, and Cost Outcomes in Patients Who Underwent Posterior Cervical Decompression and Fusion: A Single-Center Retrospective Analysis From 2008 to 2016

Dominic A. Nistal; Michael L. Martini; Sean N. Neifert; Gabrielle Price; Alejandro Carrasquilla; Jonathan S. Gal; John M. Caridi

doi:10.14444/8324

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Forest plot depicting OR of experiencing adverse clinical outcomes between patients with and without a history of obstructive sleep apnea (OSA). OSA does not impact the odds of having prolonged extubation; however, it does increase the odds of a postoperative admission to the intensive care unit (ICU). A history of OSA also decreases the odds of an extended hospitalization and nonhome discharge in our study population. OR obtained through multivariate logistic regression analysis. P value <0.05 was set as a threshold for statistical significance. *indicates <0.05; ** indicates <0.01; *** indicates <0.0001. ER, emergency room; LL, lower limit; UL, upper limit.

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Table 1

Demographics of the study population by history OSA.

Demographic	No History of OSA (n = 1098)	OSA (n = 93)	P Value
Age, y, mean ± SEM	58.8 ± 0.4	53.6 ± 1.2	0.4252
Sex, n (%)			0.1218
Male	654 (59.6)	63 (67.7)
Female	444 (40.4)	30 (32.3)
Obesity, n (%)			<0.0001^{^a}
BMI <30	1011 (92.1)	50 (53.8)
BMI 30–40	65 (5.9)	23 (24.7)
BMI >40	22 (2.0)	20 (21.5)
ASA status, n (%)			<0.0001^{^a}
I	29 (2.6)	0 (0.0)
II	512 (46.6)	16 (17.2)
III	505 (46.0)	70 (75.3)
IV	50 (4.6)	7 (7.5)
ASA status (reference: <2), n (%)
>2	556 (50.6)	77 (82.8)	<0.0001^{^a}
Admission type, n (%)			0.1261
Elective	1071 (97.5)	93 (100.0)
Nonelective	27 (2.5)	0 (0.0)
Segments operated, mean ± SEM	3.9 ± 0.06	4.2 ± 0.21	0.1066
Length of surgery, min, mean ± SEM	156.4 ± 13.7	164.6 ± 15.9	0.8624
Awake intubation, n (%)	61 (5.6)	9 (12.9)	0.1047
Elixhauser Comorbidity Index, n (%)			0.7373
<0	138 (12.6)	15 (16.1)
0	761 (69.3)	62 (66.7)
1–4	63 (5.7)	4 (4.3)
>4	136 (12.4)	12 (12.9)

Abbreviations: ASA, American Society of Anesthesiologists physical status classification system; BMI, body mass index; OSA, obstructive sleep apnea; SEM, standard error of the mean.
↵a P < 0.05 was used as a threshold for statistical significance.

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Table 2

Morbidity and mortality of the study population by history of OSA.

Variable, n (%)	No History of OSA (n = 1098)	OSA (n = 93)	P Value
Morbidity by organ system
Airway	1 (0.1)	0 (0.0)	0.7709
Acute respiratory distress syndrome	1 (0.1)	1 (0.0)	0.7709
Atelectasis	53 (4.8)	8 (13.1)	0.1128
Posthemorrhagic anemia	134 (12.2)	21 (22.6)	0.0043^{^a}
Renal failure	16 (1.5)	1 (1.1)	0.7656
Myocardial infarction	7 (0.6)	2 (2.2)	0.1057
Cardiac arrest	9 (0.8)	2 (2.2)	0.1977
Cerebrovascular attack	1 (0.1)	0 (0.0)	0.7709
Deep venous thrombosis	2 (0.2)	0 (0.0)	0.6804
Obesity-related hypoventilation syndrome	1 (0.1)	0 (0.0)	0.7709
Pneumonia	29 (2.6)	4 (4.3)	0.3491
Pulmonary edema	1 (0.9)	0 (0.0)	0.7709
Pulmonary embolism	3 (0.3)	0 (0.0)	0.6138
Pulmonary insufficiency	4 (0.4)	0 (0.0)	0.5599
Respiratory failure	15 (1.4)	4 (4.3)	0.0301^{^a}
Wound dehiscence	2 (0.2)	0 (0.0)	0.6804
Sepsis	8 (0.7)	0 (0.0)	0.4088
Septic shock	3 (0.3)	0 (0.0)	0.6138
Urinary tract infection	13 (1.2)	1 (1.1)	0.9256
Overall mortality	3 (0.3)	0 (0.0)	0.6138

Abbreviation: OSA, obstructive sleep apnea.
↵a P < 0.05 was used as a threshold for statistical significance.

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Table 3

Comparison of relevant clinical outcome measures based on the presence of OSA.

Variable, n (%)	No History of OSA (n = 1098)	OSA (n = 93)	P Value
Prolonged extubation	71 (6.5)	4 (4.3)	0.4092
Admitted to the intensive care unit	184 (16.8)	31 (33.3)	<0.0001^{^a}
Complication	209 (19.0)	27 (29.0)	0.0202^{^a}
Respiratory complication	72 (6.6)	12 (12.9)	0.0217^{^a}
Nonhome discharge	337 (30.7)	24 (25.8)	0.3017
Prolonged length of stay	343 (31.2)	28 (30.1)	0.8211
Readmission within 30 d	52 (4.7)	3 (3.2)	0.5053
Readmission within 90 d	86 (7.8)	6 (6.5)	0.6320
Emergency room visit within 30 d	33 (3.0)	1 (1.1)	0.2832
Emergency room visit within 90 d	46 (4.2)	1 (1.1)	0.1386

Abbreviation: OSA, obstructive sleep apnea.
↵a P < 0.05 was used as a threshold for statistical significance.

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Table 4

Multivariate logistic regression models evaluating the impact of obstructive sleep apnea on relative clinical outcome measures.

Outcome	OR (95% CI)	P Value
Prolonged extubation	0.66 (0.21–2.07)	0.4773
Admission to intensive care unit	2.17 (1.27–3.70)	0.0046^{^a}
Complication	1.40 (0.82–2.39)	0.2201
Respiratory complication	1.36 (0.64–2.91)	0.4224
Extended hospitalization	1.36 (0.39–4.67)	0.6287
Nonhome discharge	0.50 (0.28–0.89)	0.0181^{^a}
Readmission in 30 d	0.43 (0.12–1.53)	0.1937
Readmission in 90 d	0.54 (0.21–1.36)	0.1908
Emergency room visit in 30 d	0.25 (0.03–1.99)	0.1882
Emergency room visit in 90 d	0.18 (0.02–1.39)	0.0997

Note: Models control for demographic and intraoperative variables, including age, sex, American Society of Anesthesiologists physical status classification system status, Elixhauser Comorbidity Index, number of segments operated on, obesity, and awake intubation.
↵a P < 0.05 was used as a threshold for statistical significance.

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Table 5

Multivariate linear regression model evaluating the impact of a number of demographic, clinical, and perioperative factors on predicting direct cost.

	β (SE)	95% CI	P Value
Total Direct Cost (Model 4)		(R ² = 0.83, P < 0.0001^{^a})
Age	−27.00 (15.43)	−57.3 to 3.3	0.0805
Sex (male)	−1252.57 (399.43)	−2036.2 to −468.9	0.0018^{^a}
American Society of Anesthesiologists physical status classification system status	−209.29 (347.25)	−890.6 to 472.0	0.5468
Elixhauser Comorbidity Index	23.86 (56.87)	−87.7 to 135.4	0.6749
Number of segments operated	1830.24 (107.74)	1618.9–2041.6	<0.0001^{^a}
Obesity	−409.93 (479.36)	−1350.4 to 530.6	0.3926
Obstructive sleep apnea	632.78 (781.3)	−900.1 to 2165.7	0.4182
Length of surgery	31.37 (3.04)	25.4–37.3	<0.0001^{^a}
Crystalloids	0.23 (0.23)	−0.22 to 0.68	0.3260
Colloids	3.97 (2.45)	−0.84 to 8.8	0.1054
Red blood cells	0.51 (1.30)	−2.0 to 3.1	0.6928
Platelets	10.28 (5.88)	−1.3 to 21.8	0.0806
Fresh frozen plasma	−5.82 (1.84)	−9.4 to −2.2	0.0016^{^a}
Cryoprecipitate	352.91 (33.68)	286.8–419.0	<0.0001^{^a}
Length of stay	1301.54 (47.23)	1208.9–1394.2	<0.0001^{^a}
Intensive care unit length of stay	1229.41 (111.55)	1010.6–1448.3	<0.0001^{^a}
Awake intubation	858.09 (833.25)	−776.7 to 2492.9	0.3033

Abbreviation: SE, standard error.
Note: Multiple models were constructed to evaluating a variety of clinical factors. The table presents model 4 from Table 6 and is the most comprehensive model.
↵a P < 0.05 was used as a threshold for statistical significance.

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Table 6

Multivariate linear regression models evaluating the impact of a history of obstructive sleep apnea on predicting direct cost while controlling for a number of perioperative variables.

	β (SE)	95% CI	P Value
Total Direct Cost
Model 1	1125.66 (1720.14)	−2249.18 to 4500.50	0.5130
Model 2	−1155.54 (1602.16)	−4298.93 to 1987.85	0.4709
Model 3	−297.31 (1431.57)	−3106.04 to 2511.42	0.8355
Model 4	632.78 (781.29)	−900.12 to 2165.68	0.4182

Abbreviation: SE, standard error.
Note: Multiple models were constructed to evaluating a variety of clinical factors. Model 1 had only sleep apnea as an independent variable to predict cost as the dependent variable. Model 2 included model 1 plus age, sex, American Society of Anesthesiologists physical status classification system status, Elixhauser Comorbidity Index, number of segments, and obesity. Model 3 included model 2 plus length of surgery, total volume of crystalloids, total volume of colloids, total volume of red blood cells, total volume of platelets, total volume of fresh frozen plasma, and total volume of cryoprecipitate. Model 4 included model 3 plus length of hospital stay and length of intensive care unit stay.