Factors associated with poor sleep quality in women with cancer 1

ABSTRACT Objectives: to analyze the factors associated with poor sleep quality, its characteristics and components in women with breast cancer prior to surgery for removing the tumor and throughout the follow-up. Method: longitudinal study in a teaching hospital, with a sample of 102 women. The following were used: a questionnaire for sociodemographic and clinical characterization, the Pittsburgh Sleep Quality Index; the Beck Depression Inventory; and the Herth Hope Scale. Data collection covered from prior to the surgery for removal of the tumor (T0) to T1, on average 3.2 months; T2, on average 6.1 months; and T3, on average 12.4 months. Descriptive statistics and the Generalized Estimating Equations model were used. Results: depression and pain contributed to the increase in the score of the Pittsburgh Sleep Quality Index, and hope, to the reduction of the score - independently - throughout follow-up. Sleep disturbances were the component with the highest score throughout follow-up. Conclusion: the presence of depression and pain, prior to the surgery, contributed to the increase in the global score of the Pittsburgh Sleep Quality Index, which indicates worse quality of sleep throughout follow-up; greater hope, in its turn, influenced the reduction of the score of the Pittsburgh Sleep Quality Index.


Methods
An analytical and longitudinal study, undertaken in a Women's Comprehensive Healthcare Center, with major coverage in the state of São Paulo, covering 42 municipalities and with nearly five million people treated each year.
The study had the following inclusion criteria: women aged 18 years old or over, with a diagnosis of breast cancer, TNM 0 at any stage (8) , who were undertaking adjuvant chemotherapy and/or radiotherapy throughout the treatment, being treated in a hospital specialized in attendance to women, and receiving inpatient treatment due to mastectomy or quadrantectomy. The TNM system is the main system used in the staging of cancer, in accordance with Tumor (T), Node (N) and Metastasis (M); as an inclusion criteria, the researchers included those women in (0, 1, 2 or 3) and M0 as 'without metastasis' (8) . The exclusion criteria for the study were: Karnofsky Scale below 70 (the individual is able to care for herself for the majority of her needs, but these require a greater or lesser degree of dependence on the help of third parties); inadequate clinical conditions (such as mucositis, pain, nausea, dyspnea or vomiting) and inadequate emotional conditions (such as crying, apathy or aggression) for responding to an interview.
All the women receiving inpatient treatment due to surgery for removal of the tumor during the interval stipulated for data collection were included in the study, as long as they satisfied the selection criteria, totaling 156 participants at the beginning of the treatment (T0).
None of the women approached declined to participate. These women were monitored over 12.4 months, on average, during the clinical treatment in the outpatient centers of the above-mentioned hospital. Due to the losses to follow-up (failure to appear for interview, deaths and incompleteness of data in the medical records), the study was undertaken with 102 women who completed all four stages of the study (T0, T1, T2 and T3). Characterization Questionnaire, which was used at the beginning and end of the study. These were, namely: Mansano-Schlosser TC, Ceolim MF.

-Sociodemographic and Clinical Characterization
Questionnaire: adopted based on a study undertaken in patients with cancer (9) and subjected to content validation by specialists. This contains questions for sociodemographic and clinical characterization of the sample and was answered by the women and confirmed in the medical records by the researcher. In the medical records there were incomplete areas referent to clinical issues of the tumor such as the hormones estrogen and progesterone, or data on staging, which lead to loss to follow-up.
-The Pittsburgh Sleep Quality Index (PSQI-BR) (10) : validated in Brazil (11) . This allows the subjective assessment of sleep quality and problems throughout the month prior to the application of the questionnaire.
It contains 19 questions, grouped in seven components: subjective sleep quality, latency, duration, efficiency, sleep disturbances, use of sleeping medication and daytime dysfunction. The global score varies from 0 -21 points, and higher values correspond to worse assessment of sleep. When above five, it indicates poor sleep quality (11) .
-The Beck Depression Inventory (BDI) (12) : a selfassessment measurement of depression, broadly used in research and in clinical practice, validated in Brazil (13) . The original scale consists of 21 items, including symptoms and attitudes, whose intensity varies from zero to three.
The items refer to sadness, pessimism, a feeling of failure, lack of satisfaction, feelings of guilt, feelings of punishment, self-deprecation, self accusation, suicidal ideation, bouts of crying, irritability, social withdrawal, indecisiveness, distortion of body image, work inhibition, sleep disturbance, fatigue, lack of appetite, weight loss, somatic preoccupation and reduction in libido.
The following cut-off points were observed: below 10 -without depression, or with minimal depression; from 10 to 18 -mild to moderate depression; from 19 to 29 -moderate to serious depression; and 30 to 63severe depression (12) . Next, they were grouped into two categories: "without depression" and "with depression" (encompassing mild, moderate and severe depression).
-The Herth Hope Scale (HHS) (14) , validated for use in Brazil (15) . This is made up of 12 statements with responses on a Likert-type scale (values of 1 to 4), with the following possibilities for response: disagree completely, disagree, agree, and agree completely. The total score varies from 12 to 48 points; the higher the score, the higher the level of hope (15) .
The treatment of the data was undertaken with the support of a statistician, and consisted of the descriptive analysis and construction of the Generalized Estimating Equations model (GEE) (16) , for the identification of factors present in T0 which influenced sleep quality throughout the follow-up period. A level of significance of 5% was considered. The analysis of reliability of the PSQI-BR was undertaken using the Cronbach alpha coefficient.

Results
The 102 participants presented a mean age of 56.  Table 1. The staging of the cancer was grouped in I/II as it is considered to be initial and constituted the majority of cases in this study.      There are specific instruments, as in the present study, which can be administered by health professionals for identifying such complaints and possible illnesses, such as depression (13) .
It should be highlighted that factors such as depression, for example, if not treated, may be present for years after the clinical treatment of the cancer (2) .
Compromising of sleep quality is considered to be a factor present in depression, so much so that one question regarding this forms part of the instrument for tracking depression used in this study. Authors have argued that the attempt to establish a unidirectional causal relationship might represent a simplification of an association which is in fact fairly complex, such that depressive symptoms can lead to poor sleep quality, and changes in sleep may contribute to the presence of depression in these women (20) .
Besides depression, pain was also a significant influence on poor quality sleep in this study. It is a frequent symptom in these patients, affecting 39.2% of the women in this study. High levels of depression, anxiety and sleep disturbances were present in women with breast cancer and who reported pain, in comparison with the group of women who did not have pain (21) .

Sociodemographic variables such as age and years
of study were not significant in this study, in contrast with other authors, who showed that advanced age and fewer than seven years in full-time education were independent predictors of poor quality sleep (20) . In the present study, the majority of the women (75%) had been to school for fewer than eight years -and 50%, for fewer than four years, indicating greater homogeneity in this aspect, a fact which may explain the absence of results for this variable. This study was guided by the need to identify factors which could be associated with poor sleep quality, as well as those which could contribute to its improvement.
In a positive way -in this study -hope was shown to be effective for reducing the score of the PSQI-BR. It could, therefore, be used as a strategy by the health professionals for encouragement in coping better with the disease and the patients' day-to-day (7) .
Hope has been indicated as one of the resources for coping with breast cancer to be used in the practice of the health professionals, which could have positive consequences for sleep quality -although modest, as this study's findings suggest. Further studies are necessary for assessing specific characteristics of the relationships between the factors identified in this study, and of the mechanisms for the management of the same which contribute to maintaining sleep quality or letting it worsen; and, furthermore, to ascertain whether there is a causal relationship rather than just of association between these variables, and the extent to which the treatment of depression and pain -and encouragement to hope -could contribute to improving assessment of sleep quality, in different stages of the treatment of the cancer, these necessarily being evaluated and treated by the health professionals.
As factors limiting the study, emphasis is placed on losses to follow up due to the women not attending, and to losses of data due to the lack of completeness of the medical records, reducing the sample size and the possibility of generalization of the results.
This study contributes to the advancement of