Estimation of lung cancer diagnosis and treatment costs based on a patient-level analysis in Catalonia (Spain)

There are 53 public hospitals treating lung cancer patients at all stages of the disease in Catalonia; 10 hospitals (19%) have a thoracic surgery unit. As part of a global programme to assess cancer treatment in Catalonia, a clinical audit of lung cancer treatment was conducted on 1,186 incident patients from 23 hospitals that had a volume of at least 20 cases per year. For our study, a subset of 232 patients from the main patient sample was randomly selected from the 9 teaching hospitals (out of the 10 with a thoracic surgery unit) that diagnose over 50 patients per year; these hospitals also had information on their resource use available through electronic records. The sample size is composed of 197 patients diagnosed with non-small cell lung cancer (NSCLC) and 35 patients diagnosed with small cell lung cancer (SCLC), providing 80% power to detect as significant a difference of 2,000 Euros in the mean cost by stages in NSCLC patients, and 5,000 Euros in the mean cost by stages in SCLC patients. The power calculation was based on the assumption of a standard deviation of 5,250 Euros for NSCLC, and a standard deviation of 4,500 Euros for SCLC patients, using two-sided tests at a significance level of 0.05. All assumptions were based on previous studies [3,13]. Random samples were drawn proportionally to the percentage of patients diagnosed at each hospital in 2008. The Minimum Basic Data Set (MBDS) was the source of information available for the selection of cases.

Patients were categorised based on histology as either NSCLC or SCLC. When histology was unrecorded, patients fell into the category of “no cytohistologic confirmation” (NCC). NSCLC patients were classified by TNM stage at diagnosis [14] (regardless of the disease progression during treatment). SCLC patients were classified as having limited or extensive disease.

The permission to access the patient files was given by the Catalan Health Service (Department of Health of Catalonia). Approval for this study was given by the Clinical Research Ethics Committee of the Bellvitge University Hospital, since it was the referral Ethics Committee of the study coordinating institution.

A retrospective, descriptive analysis on resource use and a direct medical cost analysis were carried out. Resource utilisation data were collected by means of hospital administrative databases and patient files. From a hospital budget impact perspective, the aggregate and mean costs per patient were assessed in the three years following diagnosis or up to death. Both aggregate and mean costs per patient were analysed by stage at diagnosis and cost type. Mean cost per patient was also analysed by sex, age group and survival at one year from diagnosis. The categories of cost considered included (a) diagnosis (diagnostic tests, ambulatory and emergency visits, inpatient nights), (b) surgery (operating room and inpatient nights), (c) chemotherapy (day hospital and cytotoxic drugs), (d) radiotherapy (number of fractions), (e) other inpatient care (not related to diagnosis, surgery, chemotherapy or radiotherapy treatments for lung cancer, e.g., hospital admissions related to COPD or other comorbidities and palliative care), and (f) continuing care (ambulatory and emergency visits, tests, scans, biopsies, etc., made in the continuing phase). The mean costs of surgical interventions as well as chemotherapy and radiotherapy treatments were also assessed by histology and stage at diagnosis.

To assess the cost of the episodes of care in the period considered, unit costs from 2008 were obtained from two sources: from one hospital (Hospital del Mar) with a detailed analytical accounting system implemented over 10 years ago, and from the Spanish Network of Hospital Costs Database (RECH), which has data from 13 hospitals in Spain and it has been registered and accredited by the Spanish Ministry of Health [15,16]. The year of diagnosis was considered the baseline year (Year 0) with costs from later calendar years being discounted at 3%.

A descriptive summary of the patients’ characteristics was formulated, reporting age, gender, TNM stage at diagnosis and treatment received. Kaplan-Maier estimates of survival time were stratified by histology and stage at diagnosis. A descriptive analysis was done to evaluate aggregate and mean cost per patient. Mann–Whitney tests were used to identify mean cost differences between sex (male/female), age group (<65 years/≥65 years) and survival at one year from diagnosis (alive one year/dead one year); and Kruskal-Wallis tests were performed to identify differences between stages. In addition, a descriptive analysis of mean costs of surgical, chemotherapy and radiotherapy treatments were carried out. All calculations were made using SPSS for Windows 21.0.

A total of 232 cases of lung cancer were analysed, of which 172 (74.1%) were NSCLC and 26 (11.2%) were SCLC; 34 (14.7%) had no cytohistologic confirmation. Table 1 describes age, gender, staging distribution of patients at diagnosis and treatments received.

The median survival time was not estimable in Stages I, II (Table 2). The mean survival time decreased in NSCLC patients from Stage I to IV ranging from 36.3 to 10.7 months and in SCLC patients between limited disease and extensive disease from 17.0 to 9.4 months.

Table 3 shows the aggregate costs of treatment by histology, stage at diagnosis, and cost category over the three years following diagnosis or up to death. In NSCLC cases, the aggregate hospital cost of lung cancer treatment ranged from 177,320 Euros at Stage II to 1,068,133 Euros at Stage IV. The aggregated cost in Stage IV was the highest, representing 41.9% of the total cost. In SCLC cases, the aggregate cost for limited disease was assessed at 107,929 Euros, whereas the cost for extensive disease was assessed as 199,707 Euros, representing 61.6% of the total cost.

Table 4 shows the mean cost per patient of lung cancer treatment by histology, sex, age group, stage at diagnosis, survival at one year from diagnosis and cost type. Mean cost per patient in NSCLC ranged from 13,218 Euros in Stage III to 16,120 Euros in Stage II. The main cost components in global mean cost per patient in NSCLC were chemotherapy (29.5%) and surgery (22.8%). The surgical and inpatient care cost represented 58.9% in Stage I, while in Stage II it was 45.9%, decreasing its relative weight as disease stage progressed. In addition, the relative chemotherapy cost increased in more advanced stages from 5.2% in Stage I to 45.7% in Stage IV. The relative cost of other inpatient care not related to lung cancer, including comorbid diseases, was stable between stages.

In SCLC patients, the mean cost per patient with limited disease was 15,418 Euros, whereas the mean cost per patient with extensive disease was 12,482 Euros. The main cost components in the global mean cost per patient in SCLC were chemotherapy (36.1%) and other inpatient costs (28.7%).

Whereas large qualitative differences were observed between stages with regard to the aggregrate cost of treatment, the Kruskall-Wallis test did not show any statistically significant cost differences between stages in the mean cost per patient in the NSCLC, SCLC and NCC groups (p-value = 0.289, 0.140 and 0.231, respectively). Mann–Whitney tests showed statistically significant cost differences between patients who did or did not survive at one year from diagnosis in NSCLC cases (p-value = 0.002) and between age groups in SCLC and NCC patients (p-value = 0.006 and 0.009 respectively).

Table 5 shows the mean cost of surgical, chemotherapy and radiotherapy treatments by histology and stage at diagnosis. In NSCLC, the mean cost of surgical interventions ranged from 7,621 Euros in Stage IV to 10,228 Euros in Stage III. The mean cost of chemotherapy treatment ranged from 1,949 Euros in Stage I to 7,179 Euros in Stage IV. The mean cost of radiotherapy ranged from 663 Euros in Stage IV to 1,308 Euros in Stage II. In SCLC patients, the global mean cost of chemotherapy and radiotherapy treatments were 3,778 Euros and 943 Euros, respectively. In NCC patients, the global mean cost of surgical interventions, and chemotherapy and radiotherapy treatments were assessed at 8,835 Euros, 6,988 Euros and 791 Euros, respectively. Regardless of the histology, high variability was observed in the mean cost of chemotherapy treatments.