Adjusted fractional polynomial models for the relationship between age (3-degree) and disability: Best powers for age and tests of significance.

Note.All models are adjusted for sex, education, wealth, retirement status, partnership, hypertension, diabetes, obesity, smoking, physical inactivity and country (in case of SHARE).“SHARE north/west” includes Sweden, Denmark, Germany, Austria, Netherlands, Belgium, France and Switzerland; “SHARE south” includes Italy, Spain and Greece, “SHARE central” includes Poland and Czech Republic.