Table 1.

Studies associating writhing GMs with cognitive development, listed according to the age of outcome assessment.

Reference	Cohort	Outcome assessment	Cut-off points	Predictive values
Beccaria et al., 2012	N = 79born ≤ 32 weeks’ gestation	2 years Griffiths Scales of Mental Development, Italian version	Not given	Not given
Spittle et al., 2013	N = 94born < 30 weeks’ gestation	2 years Bayley Scales of Infant and Toddler Development, third edition	Abnormal vs. normal writhing GMs related to moderate to severe cognitive impairment	Sensitivity: 80%(95% CI: 44–96%)Specificity: 41%(95% CI: 31–53%)PPV: 14%(95% CI: 7–27%)NPV: 94%(95% CI: 80–99%)Accuracy: 46%(95% CI: 36–56%)
Kodric et al., 2010	N = 26born < 36 weeks’ gestation	2–3 years (mean = 28.3 months; SD = 5.6 months)Bayley Scales of Infant Development, second edition, Slovenian version	Abnormal vs. normal writhing GMs related to MDI ≤ 84 vs. MDI > 84(excluding n = 3 with cerebral palsy)	Sensitivity: 100%Specificity: 28%
Spittle et al., 2013	N = 85born < 30 weeks’ gestation	4 years Differential Ability Scale, second edition	Abnormal vs. normal writhing GMs related to moderate to severe impairment in the general cognitive ability	Sensitivity: 89%(95% CI: 64–98%)Specificity: 48%(95% CI: 36–61%)PPV: 33%(95% CI: 20–48%)NPV: 67%(95% CI: 52–80%)Accuracy: 57%(95% CI: 46–68%)
Bruggink et al., 2010	N = 60born < 34 weeks’ gestation	7–11 years (median = 9 years)Wechsler Intelligence Scale for Children-III, Dutch version	Consistently abnormal GMs to 8 weeks after term vs. normal GMs before 8 weeks after termrelated to total IQ < 85 vs. total IQ ≥ 85	Sensitivity: 67%(95% CI: 43–91%)Specificity: 71%(95% CI: 58–84%)PPV: 43%(95% CI: 23–63%)NPV: 86%(95% CI: 75–97%)

CI, confidence interval; IQ, intelligence quotient; MDI, mental developmental index; NPV, negative predictive value; PPV, positive predictive value; SD, standard deviation.