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Table 1 Variables, measures and methods of analysis

From: Surgical vs. non-surgical management of displaced type-2 odontoid fractures in patients aged 75 years and older: study protocol for a randomised controlled trial

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 test
Time-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 test
Time-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
  1. CT computed tomography, NDI Neck Disability Index, EQ-5D EuroQol, VAS Visual Analogue Scale, CCI Charlson Comorbidity Index, Katz ADL Activities of Daily Living score according to Katz, DXA double x-ray absorptiometry, AUC area under the curve