(115) Efficacy of home respiratory culture kits in cystic fibrosis patients

Background: Respiratory cultures are an important part of clinical care for cystic fibrosis (CF) patients. Telemedicine visits during the COVID-19 pandemic have not allowed for routine collection. To address this issue, the University of Michigan Adult Cystic Fibrosis Program mailed home culture kits to patients. We hypothesized that results from home sputum samples would be consistent with prior cultures obtained in sputum collected in clinic, but that self-collected throat swabs would provide false negative results. We also sought to determine the percent return rate.

Methods: Adult CF patients were sent culture kits containing a specimen cup and a throat swab. Patients had the choice to submit either sample for processing. Medical personnel provided written instructions with the culture kits and, on occasion, instructed patients on proper collection techniques via phone. Samples were then refrigerated for up to twenty-four hours before a delivery service returned the specimen to a University of Michigan laboratory for analysis. Data collected from December 2020 to December 2021 (N=77) includes percent return rate, result, source, and presence of microorganisms. Pairwise culture data of in clinic collected samples versus home collected samples within one year were included in the analysis. Descriptive statistics and Cohen κ correlation coefficient were computed for all culture data and subgroups (Table 1A-E).

Results: Of the 77 culture kits returned, 46 had corresponding clinic samples collected by the same method while the remaining 21 were collected by different methods (throat swab versus sputum sample). Overall, approximately two hundred kits were mailed to patients, with a return rate of 38.5%. A similar percentage of positive culture results were obtained with both same method of collection: sputum and throat samples (Tables 1C, D, E). However, the discordance rate between cultures collected in clinic and at home range from approximately 10-30% in our cohort. Correlation between clinic and home culture data was generally good throughout, with the exception of clinic versus home throat swabs, likely due to a low event rate in the small sample size.

Conclusions: The data suggests that overall, clinic and home culture kits provide similar positive results. However, discordance in the specific culture results was common. This observation may be due to the natural fluctuations from culture to culture in CF patients. A limitation of this study is that the cultures being compared in our study were not completed on the same day. Nevertheless, our data also indicates that collection technique may influence results for certain microorganisms. How these differences might influence antibiotic selection and treatment outcomes in the era of telemedicine requires more investigation. Furthermore, the return rate was found to be relatively low, demonstrating the need for interventions to improve patient outreach and compliance.

Acknowledgements:

References: