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Table 1 Set of candidate prognostic factors (with corresponding number of parameters) for model development

From: The Value of Preseason Screening for Injury Prediction: The Development and Internal Validation of a Multivariable Prognostic Model to Predict Indirect Muscle Injury Risk in Elite Football (Soccer) Players

Selection method Candidate prognostic factor Measurement unit Number of model parameters corresponding to PF Measurement method Data type Reliability (if applicable)
Systematic review/clinical reasoning Age Years and days 1 Date of birth Continuous N/A
Frequency of previous IMIs within 3 years prior to PHE Count 1 Medical records Discrete (treated as continuous) N/A
Most recent previous IMI within 3 years prior to baseline PHE Never (ref); < 6 months; 6–12 months; > 12 months 3 Medical records Categorical N/A
Data quality/clinical reasoning CMJ peak power Watts 1 CMJ using force plates Continuous Test-retest ICC = 0.92–0.98 [28]
PROM hip joint internal rotation difference* Degrees 1 Supine ROM test using digital inclinometer Continuous Intra-rater ICC = 0.90 [29]
PROM hip joint external rotation difference* Degrees 1 Supine ROM test using digital inclinometer Continuous Intra-rater ICC = 0.90 [29]
Hip flexor muscle length difference* Degrees 1 Thomas test using digital inclinometer Continuous Inter-rater ICC = 0.89 [30]
Hamstring muscle length/neural mobility difference* Degrees 1 SLR using digital inclinometer Continuous Intra-rater ICC = 0.95–0.98 [31]; inter-rater ICC = 0.80–0.97 [32]
Calf muscle length difference* Degrees 1 WBL using digital inclinometer Continuous Inter-rater ICC = 0.80–0.95 [33, 34]; intra-rater ICC = 0.88 [34]
BMI kg/m2 1 Composite height (cm) and weight (kg) Continuous N/A
  1. PF prognostic factor, PHE periodic health examination, IMI indirect muscle injury, ref reference category (does not count as a model parameter), WBL weight bearing lunge, CMJ countermovement jump, ROM range of movement, PROM passive range of movement, ICC intraclass correlation coefficient, SLR straight leg raise, BMI body mass index, kg kilos, m mass, N/A not applicable
  2. *Denotes between limb differences