Table 2.

Study Quality: Potential Bias

Study	Methods for Selecting Participants	Statistical Methods and Control of Confounding	Methods for Measuring Exposure	Methods for Measuring Outcome Variable	Conflict of Interest	Notes and Quality Appraisal
Compton et al.²⁸	–	Major: Inadequate number of events for analysis Moderate: Unclear statistical reporting	–	Moderate: Nurses who were not specially trained identified pressure injuries	–	LQS Strength: Used an independent cohort to validate model
Cox²⁰	–	Note on events for analysis: The author included a power analysis indicating there were enough events.	–	Moderate: Nurses who were not specially trained identified pressure injuries	–	HQS
Cox & Roche¹⁷	–	–	–	–	–	HQS
Cremasco et al.¹	–	Major: Inadequate number of events for analysis Moderate: Unclear statistical reporting Moderate: Non-independent factors included in the analysis without appropriate adjustment	–	Major: No criteria for designation of wound as a pressure injury Moderate: Nurses who were not specially trained identified pressure injuries Moderate: Limited description of the outcome variable	–	VLQS
Eachempati et al.³¹	Moderate: Restricted sampling (included only patients with LOS>6 days) Moderate: Unclear inclusion/exclusion criteria	Major: Clearly incorrect statistical methods Moderate: Inappropriate strategy for model building	–	Major: No criteria for designation of wound as a pressure injury Moderate: Nurses who were not specially trained identified pressure injuries Moderate: Limited description of the outcome variable	–	VLQS
Fife et al.²⁹	–	Major: Inadequate number of events for analysis Moderate: Unclear statistical reporting	–	Moderate: Limited description of the outcome variable	–	LQS
Frankel et al.²	Indeterminate: Individuals appear to have been excluded from the study but the inclusion/exclusion criteria are not defined	Major: Inadequate number of events for analysis	–	Moderate: Nurses who were not specially trained identified pressure injuries	–	LQS
Kaitani et al.²³	–	Major: Inadequate number of events for analysis Moderate: >15% lost to follow up or missing records/inadequate data collection Moderate: Inappropriate strategy for model building	Moderate: Variable operation is unclear	–	–	LQS
Manzano et al.²¹	–	Major: Inadequate number of events for analysis	Indeterminate: No reporting of missing data for predictor variables despite high likelihood of missing data	–	–	MQS
Nijs et al.²²	–	Major: Inadequate number of events for analysis Moderate: Problematic statistical methods with moderate implications for study findings	Indeterminate: Potential temporal ambiguity (it is possible that the predictor variable occurred after the pressure ulcer event)	–	–	MQS
O’Brien et al.¹⁹	–	–	–	Moderate: Nurses who were not specially trained identified pressure injuries	–	HQS
Sayar et al.²⁴	–	Moderate: Sampled from “high-risk” patients on a risk-assessment scale and then included attributes of the same scale as predictor variables	Moderate: Non-independent factors are included in the analysis without proper adjustment Moderate: Selective reporting of results Moderate: Unclear statistical reporting	–	–	LQS
Slowikowski & Funk⁴	–	–	–	Moderate: Limited description of the outcome variable	–	HQS
Suriadi et al.¹⁸			Moderate: Unclear statistical reporting	–	–	HQS
Tayyib et al.²⁵	–	Major: Inadequate number of events for analysis Moderate: Nonindependent factors included in the analysis without appropriate adjustment	–	Moderate: Nurses who were not specially trained identified pressure injuries	–	LQS
Theaker et al.²⁶	–	Major: Inadequate number of events for analysis Moderate: >15% lost to follow up or missing records Moderate: Nonindependent factors included in the analysis without appropriate adjustment	–	Moderate: Nurses who were not specially trained identified pressure injuries Moderate: Limited description of the outcome variable	–	LQS
Ulker Efteli & Yapucu Gunes²⁷	Moderate: Restricted sampling (included only patients with LOS>6 days)	Major: Inadequate number of events for analysis	–	Moderate: Nurses who were not specially trained identified pressure injuries	–	LQS
Yepes et al.³⁰	Moderate: Restricted sampling (included only patients on mechanical ventilation and vasopressor support)	Moderate: Nonindependent factors included in the analysis without appropriate adjustment Moderate: Unclear statistical reporting	–	Moderate: Nurses who were not specially trained identified pressure injuries	–	LQS