Participants
In this prospective observational study, 200 consecutive patients with DTC at E-Da Hospital, Kaohsiung City, Taiwan, were recruited from January 2015 to December 2018. All patients aged between 20 and 85 years who had undergone thyroid surgery, were receiving levothyroxine treatment, and did not have metastasis were included. We excluded patients with cognitive deficits that prevented them from understanding the study’s purpose or completing the questionnaire. A face-to-face interview was conducted, and they then completed—at the following two time points—a questionnaire rating their mental health status (symptoms of common mental disorders such as depression and anxiety) and HRQoL: while hospitalized for therapeutic RAI and 1 month after the treatment. The participants provided written informed consent, and the Ethics Committee of the hospital approved the present study. The participants’ demographic data and clinical history (including hypertension, diabetes, hyperlipidemia, history of psychiatric follow-up with treatment, and thyroid hormone withdrawal or recombinant human thyroid-stimulating hormone [rhTSH] use before RAI) were recorded, and free thyroid hormone (free T4) and thyroid-stimulating hormone (TSH) levels were measured at baseline.
Study instruments
The 36-item Short Form Health Survey (SF-36)
The SF-36, originally developed from the Medical Outcomes Study, has been a useful instrument in clinical practice and research (9). The Taiwanese version of the SF-36 has been validated for HRQoL assessment in the Taiwanese population (10), (11). It measures eight dimensions of health: physical functioning (PF), role limitations due to physical problems (RP), bodily pain (BP), general health perceptions (GH), vitality (VT), social functioning (SF), role limitations due to emotional problems (RE), and mental health (MH), and can also be divided into two categories: Physical Component Summary (PCS) and Mental Component Summary (MCS). Higher scores indicate a personal perception of better HRQoL.
Chinese Health Questionnaire
The Chinese Health Questionnaire (CHQ) is a 12-question, 2-reverse question, 0–1-point questionnaire used to screen somatic and psychic anxiety symptoms, social dysfunction, self-confidence, and hope, all suggestive of nonpsychotic and anxiety symptoms in common mental disorders (CMDs). The questionnaire was derived from the General Health Questionnaire, with the addition of specially designed, culturally relevant items (12). For minor psychiatric morbidities, the questionnaire had sensitivity and specificity of 70% and 95%, respectively, in a community study (13). A Cronbach’s α of 0.84 and internal consistency of 0.79 were demonstrated for the CHQ (14). The cutoff point in Taiwanese community surveys was > 4 points.
Taiwanese Depression Questionnaire
The Taiwanese Depression Questionnaire (TDQ) is an 18-question, 0–3-point questionnaire used for screening clinical depressive symptoms. It is a culturally specific depression self-rating instrument for use in Taiwan (15). It has a Cronbach’s α of 0.90 and sensitivity and specificity of 0.89 and 0.92, respectively. The cutoff point in the Taiwanese community population is > 18 points.
Statistical analysis
Descriptive results regarding continuous variables are presented as the mean ± standard deviation (SD), and categorical variables are presented as numbers and percentages. We compared the mental health status of patients with versus without recombinant human thyroid stimulating hormone (rhTSH) use before RAI. We also compared baseline HRQoL between our patients and the Taiwanese reference population (age: 45–54 years) (10). In longitudinal analyses, all factors at baseline (age; sex; body mass index; history of hypertension, diabetes, and hyperlipidemia; psychiatric follow-up and treatment history; CHQ score; TDQ score; and free T4 and TSH levels) were included in the linear regression models to identify variables that can independently predict mental health and psychiatric symptoms (using TDQ and CHQ scores as dependent variables) and HRQoL (using the scores of eight dimensions of the SF-36 as dependent variables) at 1 month after RAI therapy. All analyses were performed using SPSS version 19.0 for Windows (IBM, USA). The study was approved by the Institutional Review Board of E-Da Hospital.