A methodological approach to identify external factors for indicator-based risk adjustment illustrated by a cataract surgery register

Table 5 Results of multiple logistic regression analyses to evaluate the association between putative external factors (explanatory variables) and two outcome indicators (refractive accuracy and visual rehabilitation) 2 – 5 weeks after cataract surgery based on the combined data of three outpatient centres: Odds ratios (OR) and local 99% confidence intervals (CI) for each explanatory variable; underlying model fit assessed by Nagelkerke’s adjusted R ² criterion for the respective multiple logistic regression models

	“Refractive accuracy” │SE – TR │ ≤ 0.5 dpt		“Visual rehabilitation” visual acuity cc ≥ 1.0
Nagelkerke goodness of fit	0.03		0.12
	OR	99% CI	OR	99% CI
Sociodemographic external factors
Age ≥ 80 years	0.872	0.749–1.030	0.478	0.409–0.560
Female gender	1.120	0.981–1.289	0.915	0.808–1.045
Quantitatively documented external factors
Baseline visual acuity cc ≤ 0.1	0.705	0.567–0.891	0.568	0.433–0.698
Severe nearsightedness (myopia, axial eye length ≥ 25 mm)	0.612	0.498–0.760	0.958	0.771–1.200
Severe farsightedness (hyperopia, axial eye length ≤ 22 mm)	0.713	0.591–0.881	0.579	0.468–0.729
Qualitatively documented external factors
Presence of at least one pre-existing condition (potentially) reducing visual acuity	1.016	0.878–1.178	0.519	0.449–0.584
Presence of at least one known previous ocular surgery	1.005	0.697–1.542	0.535	0.339–0.771
Presence of at least one surgically relevant ocular risk factor	0.766	0.660–0.896	0.834	0.730–0.962
Centre contrasts
1 versus 3	0.763	0.644–0.892	1.304	1.110–1.503
2 versus 3	0.579	0.491–0.697	0.449	0.360–0.531

TR: Target refraction, SE: Spherical equivalent 2–5 weeks after cataract surgery.
Visual acuity cc: best-corrected visual acuity 2–5 weeks after cataract surgery.

ISSN: 1472-6963