Association between poor clinical prognosis and sleep duration among breast cancer patients.
Thalyta Cristina Mansano-Schlosser, Maria Filomena Ceolim
PMID 28591304WHAT IT FOUND
Women with breast cancer who slept less than six hours or nine hours and over had greater probability of disease progression, new lymph node or distant metastases, than women sleeping six to nine hours.
After accounting for other factors, sleep duration was not significant.
Key findings
01Only sleep duration showed a significant difference in poor clinical progression on log-rank testing (P=.0173).
02The probability of absence of poor clinical progression was less than 75% for sleep less than six hours or nine hours and over, and approximately 90% for six to nine hours.
03In the adjusted Cox model, sleep duration had risk ratio 2.73, confidence interval 0.99 to 7.52, P=.0518, and no factor was independently associated with poor clinical progression.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
The study used a convenience sample from one university hospital in São Paulo, so it may not represent other breast cancer patients. Only 114 of the 156 selected women were analysed because medical-record data were not recovered. Follow-up averaged 15 months and ranged from one to 21 months, and the authors state this is short for the expected outcome. Sleep was assessed by questionnaire and one-month recall, not by objective measures such as actigraphy. Only 17 women had poor clinical progression, and after adjustment sleep duration was not an independent factor. The study did not aim to establish causal relationships.
The easy way to misread this
Do not read this as proof that changing sleep duration will improve breast cancer prognosis. The study was observational, sleep was self-reported, follow-up was short, and after adjustment sleep duration was not an independent factor.