Table 6.

Correlations between highest and lowest tertiles of internal control and external control and clinical features of FM^a

Characteristics	Internal control (PCOISS)		External control (Mastery Scale)
	FM	HC	FM	HC
Pain	NS	−0.640**	−0.245	−0.450**
Fatigue	−0.340**	−0.452**	−0.347**	NS
Sleep	−0.395**	−0.399**	−0.390**	NS
Confusion	−0.618**	−0.770**	−0.679**	−0.741**
Stress	−0.453**	−0.577**	−0.443**	−0.604**
Anxiety	−0.411**	−0.416**	−0.414**	−0.454*
Depression	−0.451**	−0.610**	−0.510**	−0.583**

Notes:

^aCorrelations expressed as r-values between highest and lowest tertiles;

^*P < 0.05;

^**P < 0.0001.

Abbreviations: FM, fibromyalgia; HC, healthy controls; NS, not significant; PCOISS, Perceived Control of Internal States Scale.