Univariate | Multivariable* | Major slip† | ||||
RR | 95% CI | RR | 95% CI | RR | 95% CI | |
Slip-resistant shoes | 0.37 | 0.26 to 0.53 | 0.46 | 0.34 to 0.63 | 0.60 | 0.24 to 1.48 |
Non slip-resistant shoes | 1.00 | – | 1.00 | – | 1.00 | – |
Mean coefficient of friction‡ (0.1) | 0.66 | 0.54 to 0.82 | 0.79 | 0.66 to 0.95 | 0.46 | 0.31 to 0.66 |
Mean floor surface roughness‡, § ¶ | ||||||
Ra (1 μm) | 1.04 | 0.87 to 1.25 | ||||
Rpm (5 μm) | 0.99 | 0.81 to 1.21 | ||||
Daily floor-cleaning frequency§ | 0.88 | 0.79 to 0.99 |
↵* Adjusted for age, gender, BMI, education, primary language, job tenure and chain of the restaurants.
↵† Model includes only coefficient of friction and shoes (not adjusted for age, gender, BMI, education, primary language, job tenure and chain of the restaurants).
↵‡ Averaged coefficient of friction and surface roughness parameters at the restaurant level.
↵§ Roughness parameters and floor-cleaning frequency not significant in the multivariable model and thus dropped from the model.
↵¶ Floor surface roughness could not be measured in one location. Univariate rate ratios and 95% CIs based on data from 35 locations. Roughness parameters were dropped from the multivariable model, and analysis includes all 36 restaurants. Sensitivity analysis modelling major slips also includes 36 restaurants.