Impact of Comorbidities on the Prognosis of Pediatric Postural Tachycardia Syndrome

Figures & data

Table 1 Clinical Characteristics of Patients in the S-POTS Group and Co-POTS Group

Items	S-POTS Group	Co-POTS Group	Z/t/χ^2	P value
Number	156	119
Sex (male/female)	62/94	55/64	1.158	0.282
Age at admission, years old	12.0 (10.0, 13.7)	12.0 (10.0, 14.0)	−0.672	0.502
Age of onset, years old	11.0 (8.0, 12.0)	11.0 (7.0, 13.0)	−0.451	0.652
BMI, kg/m^2	18.3 (16.2, 20.6)	17.9 (16.2, 20.0)	−0.238	0.812
Course of disease before admission, month	12.0 (3.0, 24.0)	12.0 (4.0, 36.0)	−0.588	0.556
Symptom score at admission	5.0 (3.0, 8.0)	6.0 (4.0, 8.0)	−1.749	0.080
Supine heart rate, bpm	76.4 ± 9.8	75.1 ± 9.1	1.121	0.263
Supine systolic pressure, mmHg	107.0 (99.0, 115.0)	106.0 (99.0, 112.0)	−0.903	0.367
Supine diastolic pressure, mmHg	61.0 (56.0, 66.0)	62.0 (57.0, 67.0)	−0.615	0.539
*Maximum upright heart rate, bpm	122.3 ± 11.6	121.8 ± 13.1	0.354	0.724
^#Treatment (medication/nonmedication)	78/78	56/63	0.234	0.629

Notes: Values are mean ± standard deviation, median (P₂₅, P₇₅), or number; ^#Nonmedication therapy included health education, upright training, or oral rehydration salts; Medication therapy included midodrine or metoprolol on the basis of nonmedication therapy; *The maximum upright heart rate refers to the peak heart rate within the initial 10 minutes when the patient stands up during the standing test or when the patient is tilted during the HUTT at his or her first hospitalization. Abbreviations: BMI, body mass index; bpm, beat per minute; S-POTS, simple postural tachycardia syndrome; Co-POTS, postural tachycardia syndrome with comorbidity.

Figure 1 Flow-chart of patient inclusion. Of 364 patients with POTS, 89 were excluded according to the exclusion criteria, and the remaining 275 patients were followed up. Finally, 254 patients completed follow-up.

Abbreviation: POTS, postural tachycardia syndrome.

Figure 2 Forest plot for the outcomes of univariate and multivariate Cox regression model analysis on risk factors for prognosis in children with POTS. (A) Forest plot presenting the crude hazard ratio for the outcomes of univariate Cox regression model analysis. (B) Forest plot presenting the adjusted hazard ratio for the outcomes of multivariate Cox regression model analysis. Each blue rhombus represents the HR value of the corresponding variable, and the intersecting blue transverse line represents the 95% CI.

Abbreviations: POTS, postural tachycardia syndrome; BMI, body mass index; bpm, beat per minute; HR, hazard ratio; CI, confidence interval.

Table 2 The Spectrum of Allergic Disorders in Comorbidities of Pediatric POTS

Items	Number of Participants with Different Comorbidities	Percentage of the Number of Comorbidities (N=119, %)
Allergic disorders	99	83.2%
Allergic rhinitis	24	20.2%
Food allergy	18	15.1%
Adverse reactions to drugs	14	11.8%
Childhood asthma	5	4.2%
Atopic eczema	7	5.9%
Urticaria	3	2.5%
^#Multiple allergic disorders	28	23.5%

Notes: ^#Complicated with more than one allergic disorders, among them, 18 cases complicated with 2 allergic disorders, 8 cases complicated with 3 allergic disorders, and 2 cases complicated with 4 allergic disorders.

Abbreviation: POTS, postural tachycardia syndrome.

Table 3 The Spectrum of Psychological Disorders in Comorbidities of Pediatric POTS

Items	Number of Participants with Different Comorbidities	Percentage of the Number of Comorbidities (N=119, %)
Psychological disorders	19	16.0%
Psychosomatic illness	1	0.8%
Conversion disorder	1	0.8%
Anxiety disorder	1	0.8%
Mood disorders	9	7.6%
Depression	3	2.5%
Unspecified mood disorders	6	5.0%
Sleeping disorder	1	0.8%
Sleeping disorder and anxiety disorder	3	2.5%
Anxiety disorder and mood disorder	3	2.5%
Psychosomatic illness and mood disorder	1	0.8%

Abbreviation: POTS, postural tachycardia syndrome.

Figure 3 The spectrum of comorbidities in children with POTS. (A) The proportion of patients complicated or not complicated with comorbidities. (B) The proportion of different comorbidities of patients in the Co-POTS group.

Abbreviations: POTS, postural tachycardia syndrome; S-POTS, simple POTS; Co-POTS, POTS with comorbidity.

Figure 4 Influence of comorbidities on prognosis of pediatric POTS. The K-M curves showed the cumulative symptom remission rate in the S-POTS and Co-POTS groups during follow-up. The green curve and red curve represent the cumulative symptom remission rate for the S-POTS group and Co-POTS group, respectively.

Abbreviations: K-M, Kaplan–Meier; POTS, postural tachycardia syndrome; S-POTS, simple POTS; Co-POTS, POTS with comorbidity.

Table 4 Evaluation of Rehospitalization Burden in Children with POTS

Items	S-POTS Group	Co-POTS Group	Z	P value
Total number of rehospitalizations (time)	1.0 (1.0, 2.0)	1.0 (1.0, 2.0)	−3.368	0.001
Total hospital stay (day)	8.0 (7.0, 12.0)	10.0 (7.0, 17.0)	−3.593	<0.001

Notes: Values are median (P₂₅, P₇₅) .

Abbreviations: POTS, postural tachycardia syndrome; S-POTS, simple POTS; Co-POTS, POTS with comorbidity.