Upon completion of the 4-week treatment, patients will undergo a 4-week follow-up period. Research staff will continue to follow participants by telephone, short messaging via mobile telephone, or in the clinic. During the treatment period, follow-up will be conducted weekly. A record of symptom assessment and treatment compliance/changes will be maintained. If participants discontinue/deviate from the intervention protocols, research staff will record the reasons for the change. Such participants and their data will be excluded from the study.
Intervention in the treatment group
The patients will operate an Atmosphere® air purifier (Amway China, Guangzhou, China) in their bedrooms. This air purifier contains a HEPA two-way filter (model number 101076CH) with an airflow velocity of 100/200 cubic feet/minute at a filtration rate of 6000/12,000 cubic feet/hour. This represents 4/8 air changes per hour in a typical bedroom measuring 15 × 12 × 8 ft. The air purifier will be placed in the bedroom of the patient. Instructions will be given for the units to be left running continuously. The patients must stay in their bedrooms at night for 4 weeks (> 8 h each day).
Intervention in the control group
The patients will operate an Atmosphere air purifier in their bedrooms, but this air purifier will contain a placebo filter. This filter is also of a two-way design with an airflow velocity of 100/200 cubic feet/minute. Instructions will be given for the units to be left running continuously. The patients must stay in their bedroom at night for 4 weeks (> 8 h each day).
Concomitant care and interventions
During the treatment and observation periods, participants will be prohibited from taking medications such as antihistamines, corticosteroids, decongestants, or leukotriene receptor antagonists orally or intranasally. Only patients with severe symptoms would be permitted to use anti-allergy agents. The type of medication, dose, and use will be recorded by the patient for analysis. For other complex chronic diseases, patients must continue taking their routine medications and therapies. Research staff will record the details of the diseases, medications, and therapies in the case report.
Primary outcome measure
The visual analog scale (VAS) will be used to measure symptom severity and quality of life. The primary outcome measure is a difference in the VAS.
Secondary outcome measures
The secondary outcomes will be changes in nasal symptoms, allergy symptom scores, Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) scores, Epworth Sleepiness Scale scores, and tolerability scores for the Atmosphere air purifier.
The most important symptom is a swelling of the turbinates, which will be graded as 1 (“mild”), 2 (“moderate”), or 3 (“severe”).
Allergy symptom scores
Allergy symptom scores will be used to grade symptoms as 0 (“no symptoms”), 1 (“mild symptoms”), 2 (“moderate symptoms”), and 3 (“severe symptoms”). The symptoms graded will be congestion, sneezing, nasal itch, rhinorrhea, eye itch, ear/palate itch, eye redness, and tearing.
The RQLQ contains 28 questions covering seven topics (daily life activities, sleep, non-eye/nasal symptoms, practical problems, nasal symptoms, eye symptoms, and emotional status). The questions will be graded on a scale from 0 (“none”) to 6 (“very often/always”).
Epworth sleepiness score
The Epworth Sleepiness Score comprises eight questions about the patient’s sleepiness, which are scored from 0 (“none”) to 3 (“probably”).
Tolerability of the atmosphere air purifier
Tolerability measure of the Atmosphere air purifier is based on answers to five questions, which will be graded on a scale from 1 (“complete disagreement”) to 5 (“complete agreement”).
Collection and management of data
Research staff is responsible for data collection. The baseline variables will be age, sex, highest education level achieved, dwelling environment, career, diagnosis, results of allergen examination, disease course, family history, VAS score, nasal symptoms, allergy symptom score, RQLQ score, Epworth Sleepiness Scale score, and tolerability of the Atmosphere air purifier. Participants will be required to record the intake of any medication during this study period.
Monitoring and management of data will be performed by a third party, which will build the study database and program settings. All data will be double-imported into an electronic database by two operators. Identified input errors will be corrected until there are no discrepancies in the database. Data organisation, data coding, range checking for data values, and data conversion to ensure quality will be the responsibility of the statistician.
Statistical analyses will be carried out using SPSS v. 17.0 (IBM, Armonk, NY, USA) in the Clinical Evaluation Center of Southern Medical University (Guangzhou, China). Data will be described as the mean and standard deviation for normally distributed data, median and interquartile range for non-normally distributed data, and frequency and proportion for categorical data. All statistical inferences will be determined using two-sided tests. We will set a significance level of 0.05 and use 95% confidence intervals to measure the uncertainty of the estimate. Efficacy analyses will use last observation carried forward (LOCF) methodology to impute for cases not fully followed up during treatment. Pearson’s χ2 test will be used to compare the differences between the dropout rate and the dropout rate attributable to adverse events. Baseline data analyses (two sets) will include demographic indicators and general, primary, and secondary indicators before intervention. Measurement data will be compared using a paired t-test. For analyses of efficacy, for quantitative variables, comparisons between groups will be made by repeated measurement variance analysis and covariance analysis. For qualitative variables, comparisons between groups will be made using Pearson’s χ2 test, whereas central effects will be tested by a mixed-effects model. For rating variables, comparisons between groups will be made using the Kruskal-Wallis test. In terms of analyses of centre effects, the quantitative indicators will be tested by the general linear method, and the qualitative indicators will be tested by the Cochran-Mantel-Haenszel test methods. A logistic regression model will be used to evaluate and correct the rating variables.
This clinical trial was reviewed by the Ethics Committee of the First Hospital of Yulin in 2016. The first patient was enrolled in 2016. From the middle of 2016 to the end of 2017, 45 patients completed the treatment and observation periods. This clinical trial is expected to be completed at the end of 2018.
Researcher will assign the recruited patients anonymous recruitment numbers and de-identified data-sets will be used to perform all subsequent references and analyses. All of the collected patient information of this study will be kept confidential in compliance to the China Personal Data Protection Act. All the data will kept by the full-time manager. And the data will only be available to the researchers. All study data will be kept for 10 years.