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Background With the increasing prevalence of antibiotic resistance, real-world data on the optimal empirical second-line therapy for Helicobacter pylori are still limited. Objectives To evaluate the real-world efficacy of various second-line therapies for H. pylori. Patients and methods This was a retrospective population-based cohort study of all H. pylori -infected patients who had received the second-line treatment after the failure of primary clarithromycin triple therapy in Hong Kong between 2003 and 2018. The retreatment success rates of different second-line therapies were evaluated. Results A total of 7591 patients who received second-line treatment were included. Notably, the most commonly prescribed regimen was still clarithromycin triple therapy, but the frequency of use had decreased from 59.5% in 2003–06 to 28.7% in 2015–18. Concomitant non-bismuth quadruple therapy had emerged as the commonest regimen (from 3.3% to 43.9%). In a validation analysis, the sensitivity and specificity of retreatment-inferred second-line treatment failure were 88.3% and 97.1%, respectively. The overall success rate of second-line therapies was 73.6%. Bismuth quadruple therapy had the highest success rate of 85.6%, while clarithromycin triple therapy had the lowest success rate of 63.5%. Specifically, bismuth/metronidazole/tetracycline quadruple, metronidazole/tetracycline triple, levofloxacin/metronidazole/tetracycline quadruple, rifabutin/amoxicillin triple and amoxicillin/levofloxacin triple therapies had relatively higher success rates over 80%. Age, treatment duration, baseline conditions and first-line treatment used were associated with success rate. Conclusions Bismuth quadruple therapy was the most effective second-line regimen for H. pylori in this real-world study. Despite a very low success rate, clarithromycin-containing triple therapies were still commonly used as second-line regimens. [ABSTRACT FROM AUTHOR]

The concept of the crowding-out effect has been employed in the tourism literature to analyse complex phenomena. However, there is limited insight into the crowding-out effect on tourists by tourists, and even less into the impact of distance on the crowding-out of tourists. This paper examines the relationship between crowding perceptions, tourists' attitudes toward crowding and the consequences of being crowded out. Results from a sample of 729 international tourists in Hong Kong suggest that there is a crowding-out effect on tourists by tourists, but this has only a marginal influence on the majority. The limited crowding-out effect is induced by tourists in general rather than by a single segment. The study also investigates the effect of distance on tourist crowding. The findings reveal a decaying effect of distance on tourists' crowding perceptions, as neighbour tourists are more susceptible to tourist crowding than tourists from long-haul markets. [ABSTRACT FROM AUTHOR]