Third, the logit transformations of the ratios were fitted by simple linear regression up to the end of the follow-up period. The estimated regression line, together with survival function of the reference population beyond the follow-up limit, was used to extrapolate the lifetime survival function of the NSCLC cohort. The life expectancy of the NSCLC cohort (up to 600 months) after diagnosis

was thus CX-5461 concentration estimated. The expected years of life lost of the NSCLC cohort was defined as the survival difference between the cohort and the reference population. The method described above has been demonstrated by computer simulation [13] and proven mathematically [14]. It has also been corroborated by several examples of cancer cohorts [15] and [16]. An open access software, the iSQoL statistical package,

was used for the computation [17]. From May 2011 to April 2012, all consecutive patients with NSCLC from PR-171 supplier the outpatient oncology, chest surgery, and chest medicine departments of NCKUH were invited to participate in this study. To minimize any magnitude of overestimation of the QoL, we also consecutively screened patients admitted to the wards between November 2011 and January 2012. The inclusion criteria were realization of a lung cancer diagnosis by each participant, the absence of malignancy at another site, and each subject’s ability to understand and answer the questionnaire. In some individuals, measurements were performed repeatedly; however, each measurement was taken at least 3 months after the previous one. The 5-dimension EuroQol questionnaire (EQ-5D) [18], the Taiwanese version of which has been validated in a previous work [19], was used with face-to-face interviews to estimate the utility values of QoL. The Fludarabine nmr five dimensions assessed by the EQ-5D are mobility, self-care,

usual activities, pain/discomfort, and anxiety/depression, each of which has three levels of severity. Using the scoring function from Taiwan, these health state parameters were transformed into a utility value ranging from 0 to 1, in which 0 represented death and 1 indicated full health. The duration-to-date for each measurement was defined as the period between the date of NSCLC diagnosis and the date of interview. A kernel-smoothing (i.e., the moving average of the nearby 10%) method was used to estimate the mean QoL function [6] and [7]. The utility values of QoL beyond the follow-up period were assumed to be the same as the average of the last 10% of patients near the end of follow-up. The lifetime survival function of the NSCLC cohort was adjusted by the corresponding mean QoL function to obtain a quality-adjusted survival curve, in which the sum of the area under this curve was the QALE of NSCLC patients [6]. We borrowed the EQ-5D utility values of the age- and sex-matched general population from the 2009 National Health Interview Survey in Taiwan.