Does influenza vaccination status change physician ordering patterns for respiratory viral panels? Inspection for selection bias

Figures & data

Table 1. Clinical respiratory virus panel (RVP) testing by demographic characteristics and influenza vaccination status.

Variable	RVP (N = 292) n (%)	No RVP (N = 908) n (%)	P value
Age (years), Mean (SD)	66.8 (16.4)	71.3 (14.9)	< 0.001
Age group			0.0002
< 65 Years	122 (30.8)	274 (69.2)
≥ 65 Years	170 (21.1)	634 (78.8)
Sex			0.747
Female	171 (24.7)	522 (75.3)
Male	121 (23.9)	386 (76.1)
Vaccination status			0.204
No	170 (25.8)	490 (74.2)
Yes	122 (22.6)	418 (77.4)
Month			< 0.001
December 2015	42 (15.0)	238 (85.0)
January 2016	41 (14.3)	246 (85.7)
February 2016	65 (33.2)	131 (66.8)
March 2016	78 (32.6)	161 (67.4)
April 2016	66 (33.3)	132 (66.7)
Vaccination status of those enrolled during pre-peak influenza season*	N = 132	N = 601	0.848
No	75 (18.3)	336 (81.7)
Yes	57 (17.7)	265 (82.3)
Vaccination status of those enrolled during peak/post peak influenza season**	N = 160	N = 307	0.058
No	95 (38.2)	154 (61.8)
Yes	65 (29.8)	153 (70.2)

*Pre-peak influenza season = December 1, 2015 to February 24, 2016

**Peak/post peak influenza season = February 25, 2016 to April 30, 2016

Table 2. Odds of respiratory virus panel (RVP) testing by influenza vaccination status (unadjusted), odds of respiratory virus panel (RVP) testing by influenza vaccination status adjusted by age, and odds of RVP testing by influenza vaccination status, adjusted by age group (< 65 vs. ≥ 65 years), period, and vaccination by period interaction for the 2015–2016 influenza season.

Variable	Unadjusted Odds Ratio^1 (95% CI)	P value	Adjusted Odds Ratio^2 (95% CI)	P value	Adjusted Odds Ratio^3 (95% CI)	P value
Vaccination Status, ref. = Unvaccinated	0.84 (0.64–1.10)	0.204	0.89 (0.68–1.17)	0.396	1.00 (0.68–1.47)	0.995

¹Unadjusted odds ratio for clinical RVP testing

²Odds ratio for clinical RVP testing adjusted for age group (< 65 vs. ≥ 65 years)

³Odds ratio for clinical RVP testing adjusted for age group (< 65 vs. ≥ 65 years), period and vaccination by period interaction

Figure 1. Spline curves showing date of clinical respiratory viral panel (RVP) testing by vaccination status for 292 inpatients using multivariable logistic model with interaction of time and vaccination status.

Figure 2. Flow diagram.

Table A1. Qualifying symptoms/syndromes for acute respiratory illness.

ICD-10	Beginning ≤ 10 days ago		ICD-10	Symptoms/Syndromes
	Influenza-like Illness		J80	Acute Respiratory Distress Syndrome
J11.1	Influenza-like illness (ILI)		R50.9	Fever
J11.1	Influenza-like disease (ILD)		R09.81	Nasal Congestion
J10.1	Influenza		R09.89	Chest Congestion
J06.9	Upper Respiratory Infection (URI)		R07.0	Sore throat
J06.9	Viral URI		R68.83	Chills
R05	Cough		R52	Body Aches
J20.8	Bronchitis		R53.83	Fatigue
	Pneumonia		R06.03	Respiratory Distress
J18.9	Pneumonia (PNA)		R06.02	Shortness of Breath (SOB)
J15.9	Bacterial Pneumonia		R06.89	Difficulty in Breathing (DIB)
J18.9	Community Acquired Pneumonia	OR	R06.00	Dyspnea
J18.9	Health-care Acquired Pneumonia		A41.9	Sepsis
J69.0	Aspiration Pneumonia		E84.0	Cystic Fibrosis Exacerbation (CF)
J18.9	Evaluate Pneumonia		J98.8	Respiratory Medical, Other
J18.9	Bibasilar Pneumonia		I50.9	Congestive Heart Failure (CHF)
	Asthma and COPD		J84.112	Idiopathic Pulmonary Fibrosis (IPF)
J44.1	COPD Exacerbation		R41.82	Altered Mental Status (AMS)
J45.901	Asthma Exacerbation			AND
J45.902	Status Asthmaticus			New onset, exacerbation, or change
J45.901	Asthmatic Bronchitis			in ≥ 2 of the following symptoms with at least one
J45.901	Asthmatic Bronchitis			respiratory symptom beginning ≤ 10 days ago:
				Respiratory Symptoms:
				Cough, Shortness of Breath, Nasal Congestion, Chest Congestion, Sore Throat
				Constitutional Symptoms:
				Fever/Feverishness, Chills, Body Aches, Fatigue

Table A2. Demographic and other characteristics of patients with RVP who were enrolled in the influenza vaccine effectiveness study and those who were not enrolled.

		Enrolled in Influenza Vaccine Effectiveness Study
Variable	TotalN = 292	No(n = 123, 42.1%)	Yes(n = 169, 57.9%)	P value
Age, Years, Mean (SD)	66.8 (16.4)	68.5 (15.6)	65.6 (17)	0.133
Age Group				0.006
< 65 Years	122 (41.8)	40 (32.5)	82 (48.5)
≥ 65 Years	170 (58.2)	83 (67.5)	87 (51.5)
Sex				0.030
Female	171 (58.6)	63 (51.2)	108 (63.9)
Male	121 (41.4)	60 (48.8)	61 (36.1)
Vaccination Status				0.125
No	170 (58.2)	78 (63.4)	92 (54.4)
Yes	122 (41.8)	45 (36.6)	77 (45.6)
Months Admitted				0.008
December 2015	42 (14.4)	28 (22.8)	14 (8.3)
January 2016	41 (14.0)	17 (13.8)	24 (14.2)
February 2016	65 (22.3)	28 (22.8)	37 (21.9)
March 2016	78 (26.7)	26 (21.1)	52 (30.8)
April 2016	66 (22.6)	24 (19.5)	42 (24.8)
Vaccination status of those enrolled during pre-peak	Total	No	Yes
influenza season*	N = 132	(n = 67, 51%)	(n = 65, 49%)
No	75 (56.8)	42 (62.7)	33 (50.8)	0.167
Yes	57 (43.2)	25 (37.3)	32 (49.2)
Vaccination status of those enrolled during peak/post	Total	No	Yes
peak influenza season**	N = 160	(n = 56, 35%)	(n = 104, 65%)
No	95 (59.4)	36 (64.3)	59 (56.7)	0.353
Yes	65 (40.6)	20 (35.7)	45 (43.3)

*Pre-peak influenza season = December 1, 2015 to February 24, 2016

**Peak/post peak influenza season = February 25, 2016 April 30, 2016