Variable/Outcomes | Hypothesis | Outcome measures | Methods of analysis |
---|---|---|---|

Baseline data:
| There is no difference between the two groups | Gender, age, Katz ADL, CCI, nursing home/hospitalisation, smoking status | Absolute numbers, percentages for categorical variables and the minimum, maximum, mean, SD and quartiles for quantitative variables |

Primary:
| |||

Function | There is a clinically important difference between the two groups, with improvement comparing baseline data with data from 6 weeks, 12 weeks, and 1 year. Surgical treatment is hypothesised to be superior | NDI (0–100%) [continuous] |
Student t test, chi-square, Mann-Whitney, Fisher’s exact test.Time-dependent differences between AUC |

Secondary:
| |||

Health-related quality of life | There is a clinically important difference between the two groups | EQ-5D [continuous] |
Student t test, chi-square, Mann-Whitney, Fisher’s exact testTime-dependent differences between AUC |

Pain | There is a clinically important difference between the two groups | VAS (0–100) [continuous] |
Students t test, chi-square, Mann-Whitney, Fisher exact testTime-dependent differences between AUC |

Non-union | The non-union rate is lower in the surgical group | Bone bridge in CT [binary], mobility on extension-flexion radiographs [binary], | Chi-square test |

Mortality | The survival is greater in the surgical group | all-cause mortality [binary], time to death [continuous, censored] | Kaplan-Meier analysis, Cox regression models, additional subdistribution hazards approach |

Osteoporosis | There is no difference between the two groups | The bone density is > 2.5 standard deviations below normal DXA T-score [binary] | Chi-square |

Subgroup analysis:
| |||

septuagenarians vs. octogenarians vs. nonagenarians | Treatment effect is diminished in nonagenarians | ||

Goel-Harms technique vs. Magerl technique | There is no difference between the two groups | ||

Male vs. female | There is no difference between the two groups | ||

Sensitivity analysis:
| |||

Per-protocol analysis | All outcomes |
Students t test, chi-square, Mann-Whitney, Fisher exact test
| |

Adjusting for baseline covariates | All outcomes | Uni-and multivariate adjusted logistic regression and Cox proportional hazard models | |

Adjusting for mortality | All outcomes | subdistribution hazards approach |