title: Spatial and Temporal Analyses of Cervical Cancer Patients in Upper Northern Thailand
abstract: Background: Cervical cancer is a major public health problem worldwide. There have been several studies
  indicating that risk is associated with geographic location and that the incidence of cervical cancer has changed over
  time. In Thailand, incidence rates have also been found to be different in each region. Methods: Participants were
  women living or having lived in upper Northern Thailand and subjected to cervical screening at Maharaj Nakorn
  Chiang Mai Hospital between January 2010 and December 2014. Generalized additive models with Loess smooth
  curve fitting were applied to estimate the risk of cervical cancer. For the spatial analysis, Google Maps were employed
  to find the geographical locations of the participants’ addresses. The Quantum Geographic Information System was
  used to make a map of cervical cancer risk. Two univariate smooths: x equal to the residency duration was used in the
  temporal analysis of residency duration, and x equal to the calendar year that participants moved to upper Northern
  Thailand or birth year for participants already living there, were used in the temporal analysis of the earliest year. The
  spatial-temporal analysis was conducted in the same way as the spatial analysis except that the data were split into
  overlapping calendar years. Results: In the spatial analysis, the risk of cervical cancer was shown to be highest in
  the Eastern sector of upper Northern Thailand (p-value <0.001). In the temporal analysis of residency duration, the
  risk was shown to be steadily increasing (p-value =0.008), and in the temporal analysis of the earliest year, the risk
  was observed to be steadily decreasing (p-value=0.016). In the spatial-temporal analysis, the risk was stably higher in
  Chiang Rai and Nan provinces compared to Chiang Mai province. According to the display movement over time, the
  odds of developing cervical cancer declined in all provinces. Conclusions: The risk of cervical cancer has decreased
  over time but, in some areas, there is a higher risk than in the major province of Chiang Mai. Therefore, we should
  promote cervical cancer screening coverage in all areas, especially where access is difficult and/or to women of lower
  socioeconomic status.
authors.affiliation: Department of Statistics, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand . Email: patrinee.t@cmu.ac.th
authors.forename: Natthapat
authors.initials: N
authors.lastname: Thongsak
authors.forename: Imjai
authors.initials: I
authors.lastname: Chitapanarux
authors.forename: Prapaporn
authors.initials: P
authors.lastname: Suprasert
authors.forename: Sukon
authors.initials: S
authors.lastname: Prasitwattanaseree
authors.forename: Walaithip
authors.initials: W
authors.lastname: Bunyatisai
authors.forename: Patumrat
authors.initials: P
authors.lastname: Sripan
authors.forename: Patrinee
authors.initials: P
authors.lastname: Traisathit
keywords: Spatial and temporal analyses; quantum geographic information system; cervical cancer; Thailand