Design, Setting and Patients: One hundred twenty one metastatic prostate cancer patients and primary caregivers were enrolled in this descriptive cross-sectional study from October 2019 to October 2020. Patients aged 50-91 years who have had the illness for three months or more, followed-up in Gazi Yasargil Training and Research Hospital. Additionally, the primary caregivers of the patients who gave consent for participation were enrolled in the study. The diagnosis of metastatic prostate cancer was confirmed with Galium-68 prostate specific membrane antigen positron emulsion tomography.
All patients and their primary caregivers (spouse or children) were evaluated in the same meeting room at the Medical Oncology Department of Gazi Yasargil Training and Research Hospital. The evaluation was performed by a medical oncology specialist.
Inclusion Criteria: Patients with metastatic prostate cancer who had at least one bone, lymph node or visceral metastasis who had undergone androgen deprivation or chemotherapy treatments for at least 3 months were included.
Exclusion Criteria: Patients who had an additional uncontrolled chronic disease such as severe hypertension, dis-regulated diabetes mellitus, any hearth disease, any type of ischemic cerebrovascular disease and any type of baseline orthopedic failure that causes mobilization defect, were excluded from the study. The exclusion criterion for hypertension was blood pressure above 170/100 mm / hg in at least 2 consecutive measurements despite using antihypertensive drugs. Diabetic patients with an HbA1c level above 7.5 or using insulin therapy or using more than one oral anti-diabetic agents were excluded. Patients with an HbA1c level below 7.5 with metformin treatment or single oral anti-diabetic therapy were included in the study. The exclusion criteria of diabetic patients were evaluated according to the relevant age group recommendations of the American diabetes association [13].
Data Collection and Questionnaires: Two self-administered surveys were completed by caregivers as follows:
Short Form 36 (SF-36): This questionnaire was applied to patients. McHorney et al performed analysis of cross-sectional data, physical and mental health status with 36-item short form questionnaire. Survey includes a comparison with traditional psychometric and clinical tests. Principal component analysis method was used for the assumed physical and mental health analysis. Physical health analysis includes assessments stratified by the severity of the chronic medical condition while measuring physical function and physical role limitations. It also evaluates role limitations and emotional status in terms of mental health [14]. SF-36 questionnaire contains sub-results such as physical function (PF), physical role (PR), bodily pain (BP), general health (GH), vitality (V), social functioning (SF), emotional role (ER) and mental health (M).
ZCBI Caregiver Burden Interview (ZCBI): This questionnaire was applied to caregivers whom were patients' relatives. ZCBI was created by ZCBI et al. [15] in 1980 as a caregiver self-report measure. The revised version of this scale consists of 22 items about physical health, psychological well-being, financial status and interpersonal relationships to evaluate caregiver burden and the impact of the patient’s disease on a caregiver’s life [15]. Ozlu et al. [16] developed the Turkish-validated ZCBI. On investigating the validity and reliability of the Turkish-language version, three items (numbers 1, 4 and 16) were removed. Hence, the Turkish-language version consists of 19 items. The scale was developed to be self-administered; however, it can also be administered by an interviewer. In the present study, the interviewer read each item aloud and asked the respondent to state their answer. Each item is scored from 1 to 5, 1 = never, 2 = rarely, 3 = sometimes, 4 = quite frequently, and 5 = nearly always. Caregiver burden is evaluated on the basis of the total score obtained from the sum of the responses. The total scores were calculated to be between 19 and 95 points, and higher scores indicating higher caregiver burden. A score of 21 or less indicates no burden, 22–46 indicates mild burden, 47–55 means moderate burden and 56 or more indicates severe burden.
Stratification Factors
Patient related clinical factors: Age, comorbidities, ECOG score, presence of bone metastatsis, presence of bone-related event and organ metastasis were determined. The bone-related event was defined as the need for opioid use due to severe bone pain or as an incurred bone fracture.The number of bone metastases was also stratified as 0, 1-3 and >4 metastases. The reason for this stratification method was that the cut off value for the distinction between oligometastatic disease and diffuse metastatic disease had been generally considered to be between 3 and 5 metastases by most authors [17, 18].
Treatment related factors: All patients received androgen deprivation therapy. The treatment related factors were chemotherapy which was accepted as active receiving in terms of cross sectional data collecting. History of chemotherapy within six months was included as active chemotherapy too. In addition, whether the patients received palliative radiotherapy, prostatic region radiotherapy and prostatectomy was also planned to examine.
Economic and educational factors: Patient educational status, personal vehicle presence or public transport usage of family, place of residence (city center, village), residence status (own house - rent) were determined
Caregiver-related factors: Caregiver age, the degree of proximity of caregivers such as spouse, child, sibling or other relatives, caregiver education and caregiver comorbidities were identified as caregiver-related factors.
Statistical Analysis and Ethics
Statistical analysis of the data was performed using Statistical Package for Social Sciences (SPSS) software version 15 (SPSS Inc., Chicago, IL, USA). First, we examined caregivers’ and patients’ characteristics. The caregiver and patient characteristics are presented as the number and percentage. Data are presented as the mean ± standard deviation (SD) or median (minimum-maximum) according to the distribution of the data. Normality of the distribution of continuous variables was determined using the Kolmogorov–Smirnov test. The mean differences between two independent groups were compared using the independent samples t–test for normally distributed variables and Mann–Whitney U test for non-normally distributed variables. The differences among three independent groups were compared using one-way ANOVA with the Tukey post hoc test for normally distributed variables and the Kruskal-Wallis test with Bonferroni correction for non-normally distributed variables. Finally, the correlations between ZCBI and SF-36 scores were assessed. The correlations between variables were assessed using Pearson or Spearman correlation coefficients for normally or non-normally distributed variables, respectively. A p value < 0.05 was considered statistically significant.
This study was approved by The Gazi Yaşargil Training and Research Hospital Ethics Board (25.09.2020/564) and was applied in accordance of the Declaration of Helsinki. Informed consents were obtained from each participants and caregivers.