The sample size was calculated using a two-independent-sample mean comparison formula, with a significance level (α) of 0.05 (two-sided) and statistical power (1- β) of 80%. The formula n = 2σ² (Zα/2 + Zβ)²/(μ1 - μ2)² was applied. The calculation indicated a minimum requirement of 76 cases per cohort. Accounting for a 20% potential attrition rate, the target sample size was set at ≥ 90 cases per cohort. The parameters for the mean values (μ1, μ2) and standard deviation (σ) were based on a preliminary pilot study conducted at Baoding Hospital, Beijing Children’s Hospital affiliated to Capital Medical University, which measured the same nutritional indicators in a smaller cohort of Hp-infected children.
From May 2018 to May 2020, a total of 225 pediatric patients diagnosed with Hp infection at Baoding Hospital, Beijing Children’s Hospital affiliated to Capital Medical University and successfully treated with triple therapy were enrolled as the study cohort. The cohort included 123 males and 102 girls, with a mean age of 10.5 ± 2.8 years. The control cohort consisted of 106 healthy children who were recruited from those undergoing routine physical examinations at the hospital during the same period. All control subjects were rigorously screened to ensure they met the following criteria: (1) No history of chronic medical conditions (including cardiac, hepatic, renal, neurological, or hereditary metabolic diseases); (2) no acute infectious diseases within the previous month; (3) not taking any long-term medications or nutritional supplements; and (4) no gastrointestinal symptoms. Crucially, active Hp infection was definitively ruled out in all control participants using the ¹³C-urea breath test, with a negative result required for inclusion. This cohort consisted of 59 males and 47 females, with a mean age of 10.5 ± 2.8 years. The two cohorts did not exhibit any significant differences in age or sex distribution (P > 0.05).
Diagnostic Standards for Hp Infection: A positive result from the rapid urease test, endoscopic pathological staining, and/or the ¹³C‐urea breath test was used to diagnose Hp infection (
8).
Eligibility criteria for selection: (1) Age ranging from 6 to 16 years; (2) absence of antibiotic or proton pump inhibitor use in the preceding month; (3) able to cooperate with comprehensive Hp infection testing; (4) able to complete a one‐year follow‐up.
Exclusion criteria: (1) Presence of severe cardiac, hepatic, renal, neurological, or hereditary metabolic diseases; (2) acute infectious disease within the previous month's history; (3) use of nutritional supplements within the past six months.
Treatment regimen: All children diagnosed with Hp infection received triple therapy, consisting of an oral proton pump inhibitor and two antibiotics, primarily including amoxicillin, for two weeks. Four weeks after the treatment, a ¹³C‐urea breath test was performed to assess eradication efficacy. Throughout the entire study period, including the one-year follow-up after successful eradication, all children were instructed not to take any iron supplements, vitamin D supplements, multivitamins, or other medications that could directly influence the measured nutritional parameters. Details of the procedures for screening, grouping, and follow-up of the children are provided in
Figure 1.
Flowchart of patient selection, grouping, and follow-up (abbreviations: Hp, Helicobacter pylori; GI, gastrointestinal)
Sample collection: A 6 mL sample of fasting venous blood was collected in the morning from all participants.
Height and weight measurement: Height and weight were measured under the same conditions for all enrolled children, in the morning after voiding and defecation, and before breakfast.
Nutritional marker measurement: For children with Hp infection, nutritional markers were assessed prior to the commencement of treatment and at the one-year follow-up. Testing for the control cohort was implemented once only at the time of enrollment (baseline). The Abbott i2000 chemiluminescence analyzer and reagents supplied by Abbott were employed to ascertain serum 25-hydroxy vitamin D3 [25-(OH)D3] content. The Mindray BC-5300 automatic hematology analyzer was employed to measure hemoglobin (Hb). The BECKMAN COULTER AU5800 biochemical analyzer was employed to detect the levels of serum iron (SI), serum ferritin (SF), and prealbumin (PA). Serum ferritin reagents were acquired from Abbott, while SI and PA reagents were obtained from BECKMAN COULTER. The Baoding Key Laboratory of Clinical Research on Children's Respiratory and Digestive Diseases conducted all laboratory analyses.
The interpretation of nutritional marker levels was based on established pediatric reference ranges. Serum 25-(OH)D3 levels were classified as sufficient (> 30 μg/L), insufficient (20 - 30 μg/L), or deficient (< 20 μg/L) according to the guidelines from the global consensus recommendations on prevention and management of nutritional rickets. Anemia was defined according to World Health Organization (WHO) criteria for age and sex, with Hb cut-offs ranging from 115 g/L for children under 12 years to 120 g/L for children aged 12 years and above. Serum ferritin levels below 15 μg/L were considered indicative of iron depletion (
9). Prealbumin levels were interpreted using age-adjusted reference values provided by the reagent manufacturer (Beckman Coulter) and our institutional laboratory guidelines. Serum iron reference ranges were also based on age-specific norms from our clinical laboratory.
3.1. Statistical Analysis
The software SPSS25.0 was employed to conduct every analysis of statistics. The mean ± standard deviation (x̄ ± s) was used to represent the information obtained from the measurements. Variance analysis and t-tests were implemented to evaluate comparisons between cohorts. A P-value of less than 0.05 was utilized to define statistical meaning. To address the issue of multiple comparisons, the Bonferroni method was used to adjust the significance level (α = 0.05/number of comparisons). All reported P-values are the results after correction.