The remaining specimen type information was summarized into one record for each report date. After completing step 1 and step 2, only one specimen type was

kept. However, on the same report date, the specimen type information from different test methods or different specimen still existed in the database and needed to be removed. For example, ‘BMA, PB’, ‘BMA, TBP’, and ‘CHIM’ were all on the same report date, and, therefore, they could be summarized into one record: “BMA, PB, TBP, CHIM”. All in all, the main task in step 3 was to summarize and combine all the remaining specimen types into one integrated specimen record. After step 3, each report date would only have one summarized specimen type, while the unnecessary pieces of information were removed from the database.

3.8 Preliminary analysis method (HILIS)

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3.8 Preliminary Analysis Methods for the HILIS database

All statistical analyses and data manipulation tasks, such as summarizing the duplicated data and calculating the lab cost, were done with the SAS/Stats application (SAS software program package, version 8.02, SAS Institute, Cary, NC)

3.8.1 Treatment phase / Length of treatment phase

Treatment phase (for example first remission or first relapse) is an important piece of information for describing the progression of AML treatment, while it is also relevant to the process of deciding the treatment types and calculating treatment costs. To identify the cutting-off date for the treatment phase, test result data from the HILIS database were used.

To identify this cutting-off date, two pieces of information were essential, namely the fields ‘test result’ and ‘date’. More specifically, the ‘report date’ was used as the cutting-off date instead of the screen date. Also, multiple test results were used for identifying the treatment phase. A breakdown of this can be found below:

a. Remission date

When the test result was firstly described as ‘remission bone marrow’ or ‘no evidence of disease’ based on specimen BMAT, then the report date could be defined as the first remission date. After that, all the following remission results could be treated as if the patient stayed in remission until the disease relapsed. If the disease relapsed, and the patient achieved remission again (that is if the patient had remission diagnosis again), then the report date for this remission would be defined as the next successive remission date (for example: second remission, third remission and similar).

b. Relapse date

Relapse is defined as the reappearance of leukemic cells after a patient achieved remission. Therefore, when a patient had previous remission record (achieved remission) and the test results were AML relevant diagnosis, then the first report date could be defined as the first relapse date. It is worth to note that ‘suspicious of malignancy’ was not considered as one of the AML relevant diagnoses. After that, if a patient had achieved

3.8 Preliminary analysis method (HILIS)

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another remission, then the report date of the following first AML diagnosis could be defined as the next successive relapse date (for example: second relapse, third relapse and similar).

It is also worth noting that a patient could have more than one remission and relapse dates depending on the diagnosis results in the HILIS database. All these dates were recorded with ordinal numbers according to the frequency of their appearances in the database (for example: 1st remission date, 2nd remission date, and 3rd remission date).

After the remission dates and relapse dates were identified, the length of treatment phase was calculated in order to present the differences and characters of each treatment phase.

3.8.2 Laboratory costs

To estimate the laboratory costs, two pieces of information were needed, namely:

‘quantity’ and ‘unit cost’. The details of these two elements are described below:

a. Quantity

The laboratory costs were calculated using 1767 test reports from the HILIS database, after the data had been cleaned. Based on the specimen type information (as shown in Table 3.2), each report had only one summarized specimen type. This summarized specimen information could be taken as ‘quantity’ in laboratory cost estimation.

b. Unit cost

For the laboratory cost calculation of each test request the price list was used as unit cost.

The price list was derived from the ‘Provider-Provider Tariff 2006-7 of the Haematological Malignancy Diagnostic Service at St James’s Institute of Oncology, Leeds Teaching Hospital NHS Trust’. The detailed price list is shown in Table 3.3.

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The test cost of each report could be obtained simply through the use of addition, by linking the unit cost to the specimen type information in the HILIS database. The test costs were further summed up by patient level. Finally, each patient would be allocated one total lab cost, and the difference of the lab cost for each patient could then be revealed.

In addition to considering the lab cost as a whole, the lab cost could be further divided by the treatment phase. This could provide a whole picture of the lab test usage in each treatment phase.

Table 3.3 Price list of specimen test

Full name of the specimen test Abbreviation Price

Bone marrow aspirate BMA £148

Bone narrow aspirate & Trephine biopsy BMAT £339

Cerebral spinal fluid (CSF) CF £29

Chimerism, allograft CHIA £265

Chimerism, baseline CHIB

Chimerism, mini-allograft CHIM

Skin, block DBL £218

Skin, fixed DF

Skin, fixed & unfixed DFU

Skin, unfixed DU

Effusion EF £90

Haematological slide HS £29

Lymph node biopsy, fixed LF £90

Lymph node biopsy, unfixed LU

Peripheral blood PB £148

Peripheral blood, stem cell PBS £148

Spleen, unfixed RU £200

Bone marrow trephine, fixed TBP £218

Miscellaneous tissue aspirate XA £148

Miscellaneous tissue, block XBL

Miscellaneous tissue, unfixed XU

3.9 Overview (HILIS)

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3.9 Overview of the work done on the HILIS database

The HILIS database was used for identifying treatment phase and for laboratory test cost calculation. In order to obtain the relevant information, the HILIS database was handled through several processes (discussed in sections 3.7). The whole process and number of cases are illustrated in Figure 3.9.

After the study database was set up, a number of preliminary analyses were conducted (please refer to section 3.8). The relevant results are presented and discussed in the next chapter (chapter 4).

Figure 3.9 Illustration of data handling process on HILIS database

3.10 Database description (PCD)

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