The prevalence of self-reported chronic fatigue in a U.S. twin registry

Abstract

Objective: To investigate the prevalence and correlates of various definitions of self-reported lifetime fatiguing illness in a U.S. twin registry.

Methods: Data from 4591 female and male twins from the population-based Mid-Atlantic Twin Registry were available for this study. Variables representing different definitions of lifetime fatiguing illness and personal characteristics were obtained through questionnaires. Odds ratios and 95% confidence intervals were calculated as measures of association between fatigue and gender. Kaplan-Meier curves were produced to examine the age at onset for lifetime fatiguing illnesses.

Results: Prevalences for different definitions of self-reported lifetime fatigue ranged from 36.7% for any fatigue to 2.7% for chronic fatigue syndrome-like illness. Females were two to three times more likely to report fatigue than males. Gender differences increased as fatigue definitions grew more restrictive. Ages at onset of chronic fatiguing illness were significantly earlier and the number of ancillary symptoms was greater for females than males. People with lifetime fatigue had significantly more compromised functional status than people without lifetime fatigue.

Conclusion: The prevalence of self-reported lifetime fatiguing illness varied widely depending upon how it was defined. Given the debilitating consequences of fatiguing illnesses, the reasons for the female predominance and the earlier onset in women should receive increased research priority.

Fig. 1

Flowchart depicting the definitions of lifetime fatigue-related conditions arranged in increasing severity (top to bottom) in the MATR. The pie charts in each box show the proportion of males (light purple) and females (dark purple). Details regarding symptom histogram and exclusionary conditions are shown.

Fig. 2

Distributions of specific symptoms reported by males (light purple) and females (dark purple) in the MATR. The x-axis depicts the eight symptoms asked of participants. The final column on the x-axis represents how many males and females endorsed having ≥4 symptoms. The y-axis represents the proportion of participants that answered “yes” to having the specific symptom.

Fig. 3

Age at onset curves for lifetime fatigue-related conditions of increasing severity stratified by gender. The y-axis depicts the proportion of the sample that had not developed a particular definition of fatigue. The x-axis depicts participant age in years. The green line shows the male estimates, while the red line shows the female estimates. For each fatigue definition, the male and female age at onset curves were different at the P <.001 for both the Wilcoxon and log–rank tests after correction for nonindependence of twin pairs.