The associations of comorbidities and consumption of fruit and vegetable with quality of life among stomach cancer survivors

Between April and June in 2015, participants were recruited from seventeen multi-community cancer rehabilitation centers, all of which were affiliated Shanghai Cancer Rehabilitation Club (SCRC), Shanghai, China, a non-government organization serving cancer survivors exclusively. It covered all the 17 districts in Shanghai and has about 13,500 cancer survivor members in Shanghai by the end of 2014. This self-help support group aiming at improving survivors’ quality of life regularly offers rehabilitation activities including physical exercise, relaxation training, nutritional and dietary counseling, psychotherapy and a variety of leisure aactivities [25]. The criteria for study enrollment are at least 16 years of age, stomach cancer as the first primary cancer, completed active treatment, able to independently participate in the activities of cancer rehabilitation club, and no cognitive impairment.

Total 1354 SCS have registered in the SCRC by the end of 2014 meet the above inclusion criteria. All members of the SCRC who intended to continue to participate in the SCRC were required to register annually, including both former and new members. The survey invitations were sent through short text messages or/and phone calls to all 1354 SCS. Among all these SCS, 131 were unable to reach because of deaths, migration or refusing to response; 254 failed to participate the survey either because they had no time, or because their health status or literacy ability was too poor. Finally, 969 (71.57%) participated this survey and formed our final sample, and completed the self-administered questionnaire, in his/her own home, or community activity center affiliated SCRC, which normally took 40–60 min.

Vegetables intake was obtained using the choice question “How much vegetables do you eat?”. The options were “≤50 g/day”, “>50g/day and ≤100g/day”, “>100g/day and ≤150g/day”, “>150g/day and ≤250g/day”, “>250g/day and ≤500g/day” and “> 500 g/day”. Fruit intake was obtained using choice question “Do you eat fruit?”. The options were “No”, “1 time/week”, “2 times/week”, “3 times/week”, “4–5 times/week”, “Everyday”.

The QOL was measured by the European Organization for Research and Treatment quality of life version 3 questionnaire (EORTC QLQ-C30) simplified Chinese version [26]. The EORTC QLQ-C30 core questionnaire contains five functional scales (physical, role, cognitive, emotional, and social), three symptoms scales (fatigue, pain, and nausea and vomiting), a global health scale, a number of single items assessing additional symptoms commonly reported by cancer patients (dyspnea, appetite loss, insomnia, constipation, and diarrhea) and financial impact of the disease. For most items, four response categories from 1 (not at all) to 4 (very much) are employed; two items (overall health, overall quality of life) have response categories ranging from 1 to 7. The scoring systems are organized such that a high scale score represents a higher response level. Thus a high score for a functional scale, the global health status or overall QOL represents a high or healthy status or a high QOL; however, a high score for the symptom scales represents a high level of symptomatology or problems. The scoring of the EORTC QLQ-C30 items was performed according to the EORTC scoring manual [27].

Standard statistical methods were used to examine potential differences in covariates by one-way analysis of variance (ANOVA) for continuous variables followed by Bonferroni post hoc tests. Comorbidity, vegetable intake, and fruit intake were conducted in the statistical analyses as dichotomous variables (yes/no, ≥250 g/day /< 250 g/day, and everyday/not every day, respectively). Means and standard deviations were calculated for continuous variables, and numbers and percentages were computed for categorical variables. Multiple linear regression models were used to compute regression coefficients (β) and associated 95% confidence intervals as estimates of the mean difference of QOL scores associated with the presence or absence of comorbidities, adjusting for potential confounding variables. The following potentially confounding variables were included in all regression models: age (continuous), Body Mass Index (continuous), years since diagnosis (continuous), household income (continuous), education (junior high school or less, senior high school or vocational school, and junior college or above), and current marital status (married/living with partner or divorced/widowed/ separated/single). Linear regression was applied to each of the variables measured in EORTC QLQ-C30. Comorbidity and other diseases (hypertension, diabetes mellitus, etc.) were not included in one model. Statistical tests were based on a two-tailed probability with a significance level of 0.05. Statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) for Windows (Version 21.0).

The characteristics of the participants are shown in Table 1. Forty-four percent of the sample was 60 years old or above. Majority of them were married (89.2%) and had at least one comorbidity (76.7%). 15.1, 63.8 and 21.1% of the participants were underweight, normal weight and overweight or obese, respectively. In terms of the types of comorbidity, the proportion of SCS who suffered from digestive diseases (49.8%) was the highest. Other comorbidities are listed according to their prevalence as follows: hypertension (30.4%), diabetes mellitus (12.8%), heart diseases (22.9%), stroke (6.7), respiratory diseases (12.3%), musculoskeletal diseases (29.6%). 38.7% of the participants ate more than 250 g vegetables every day, and 58.1% of participants who ate fruit every day.

The association between comorbidities and adjusted scores of QOL is presented in Table 2. The participants with self-reported CCD generally reported lower scores for most EORTC QLQ-C30 scales when compared to subjects without these CCD, indicating poorer QOL. The influences of diabetes, heart diseases, stroke, respiratory diseases and musculoskeletal illnesses or digestive diseases on EORTC QLQC30 scores were of a similar magnitude and were larger than the influence of hypertension.

The association between consumption of fruit and vegetable and adjusted scores of QOL is presented in Table 3. The participants who ate more than 250 g vegetables every day, and participants who ate fruit every day, reported higher scores in most functioning subscales and lower scores in some symptoms subscales than participants who ate equal or less than 250 g vegetables every day, and participants who didn’t eat fruit every day, respectively, indicating better QOL.