Testing Gender as a Moderator of Associations between Pain and Depressive Symptoms in Advanced Cancer Patients: A Cross- Sectional Study in Singapore

Pain and depressive symptoms are prevalent in cancer patients with previous studies showing that pain increases the risk of depressive symptoms among cancer patients. Though researchers have identified gender differences in the association between pain and depression in healthy pediatric populations in the U.S., little research has been conducted about the same association with cancer patients or in Singapore.

In this study, we aim to first assess the proportion of advanced cancer patients in Singapore presenting to the National Cancer Center Singapore (NCCS) and Singapore General Hospital (SGH) during 2016 – 2017, who have pain conditions as well as the proportion of the patients with depressive symptoms. We are also interested to evaluate whether the positive association between pain and depressive symptoms previously identified in cancer patients holds in advanced cancer patients approaching their end of lives. Finally, we aim to test the moderating effect of gender on the association between pain and depressive symptoms in this special population.

Our sample comprised 377 outpatient advanced cancer patients recruited from the National Cancer Center Singapore (NCCS) and Singapore General Hospital (SGH) during 2016 - 2017. We administrated Brief Pain Inventory (BPI)- Short form for pain assessment, and Hospital Anxiety and Depression Scale (HADS)- Depression Subscale for depressive symptoms. In multivariate analysis, we used Negative Binomial (NB) regression to estimate the association between pain severity / pain interference and depressive symptoms, and the moderating effect of gender in these associations, while controlling for age, education level, and ethnicity.

We found that 74.40% patients had pain conditions, and 6.20% of them had depressive symptoms. We have also identified a positive association between pain severity and depressive symptoms, as well as between pain interference and depressive

symptoms. We did not find evidence that gender moderates the association either between pain severity and depressive symptoms, or between pain interference and depressive symptoms.

The positive association between pain and depressive symptoms in advanced cancer patients suggests equal necessity to assess and treat pain as well as depression in palliative care settings because they often coexist. There is no strong evidence that physicians should tailor pain and depression management to male and female patients since no significant gender difference was observed in the association between pain and depressive symptoms.