Table 2.

Valid prediction models

	Completers (n = 121)			Discontinuers (n = 38)
	Outcome variable
Baseline variable	Function‐PCS	QoL‐EQ5D	QoL‐MCS	Discontinuation during titration
HADS‐A		−0.17*
HADS‐D			−0.41***	1.33**
EQ‐5D VAS	−0.15	−0.73***
painDETECT‐6	0.27**	0.20**	0.38***
PDQ burning				0.80*
PDQ attacks			−0.20*
SF36 MCS	0.31***		−0.71***
SF36 PCS	−0.32***
Sex female	−0.22**			1.45
Coefficient of determination; c‐statistics	$R_{\mathrm{adj}}^2$  = 0.31, $R_{\mathrm{adj},\mathrm{corr}}^2$ = 0.21	$R_{\mathrm{adj}}^2$  = 0.54, $R_{\mathrm{adj},\mathrm{corr}}^2$ = 0.47	$R_{\mathrm{adj}}^2$  = 0.41, $R_{\mathrm{adj},\mathrm{corr}}^2$ = 0.35	c‐statistic = 0.68, c‐statisticcorr = 0.61

Parameters of statistical models using the standardized variables. This type of presentation allows the comparison of the influence of the baseline variables on the outcome variables – the larger the absolute value of the respective parameter the stronger the influence. A significant relationship is indicated by *p < 0.05, **p < 0.01, ***p < 0.001. For all outcome measures, the corresponding baseline value has the highest impact on prediction (e.g. baseline MCS predicts outcome MCS, baseline PCS predicts outcome PCS). The results are shown for the models with the modified 6‐item painDETECT score (painDETECT‐6).

For the linear models, the coefficient of determination (R ²) is shown. The coefficient of determination is a number that indicates how well data fit a statistical model. An R ² of 1 indicates that the regression line perfectly fits the data, while an R ² of 0 indicates that the line does not fit the data at all (see text). For the binary model, the c‐statistic is the measure for the global fit of the model. The c‐statistic is also referred as area under the curve (AUC), which is the area under the ROC curve. The receiver operating characteristic (ROC) is a plot which illustrates the overall diagnostic performance by plotting the outcome related sensitivity vs. specificity for each value of the predictive model (Fig. 6).

NRS‐3, Pain Intensity Score in the last three days; SF36 MCS, Short Form 36 Health Survey, mental component summary scale; SF36 PCS, Short Form 36 Health Survey, physical component summary scale; EQ5D VAS, EuroQol‐Health State Today; HADS‐A/D, Hospital Anxiety and Depression Scale; PDQ, painDETECT questionnaire; painDETECT‐6, modified painDETECT score using six items excluding the item “painful attacks”.