Study selection phase 1: selection criteria

In document CANCER TREATMENT PATHWAYS: AML A DETAILED COSTING STUDY EXAMPLE HAN-I WANG. PhD (Page 38-42)

AUTHOR’S DECLARATION

CHAPTER 2 LITERATURE REVIEW

2.2 Study selection phase 1: selection criteria

The research was limited to English language articles published between 1995 and 2007.

All types of cost studies (such as cost analysis, cost effectiveness analysis, and cost utility analysis studies) on AML/APML were included. The details are discussed in the following sections, while the summarized criteria are listed in Table 2.1.

2.2.1 Participants

Inclusion criteria:

Studies in which patients were newly diagnosed with Acute Myeloid Leukemia (AML) and/or Acute Promyelocytic leukemia (APML / APL) were included, regardless of age and treatment phases.

Exclusion criteria:

Studies in which patients who were not diagnosed with AML or APML were excluded.

a. AML /APML

Studies that recruited both AML and APML patients were included. The reason for this was that the treatments and the clinical manifestations of APML were significantly different from the ones of AML, although APML is a common subtype of AML (accounts for 5-10% of cases of AML) [52, 53]. In the current review, studies focusing exclusively on APML or on both AML and APML were all included. It is worth noting that studies that included various haematological cancers (in which only a minor part concerned AML/APML) were excluded, as the relevant study designs, measurement methods, and results had little correlation with AML/APML.

Table 2.1 Summary of the study selection criteria

Inclusion Exclusion

Population Newly diagnosed AML / APL Not AML / APL studies or only a minor part discusses about AML Intervention Economic evaluation analysis Clinical management analysis

Outcome Costing method No relevant methods

Language English studies Non-English studies

Publication status Published and unpublished -

Publish year 1995-2008 Before 1995

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b. Newly diagnosed

Studies that recruited ‘newly diagnosed’ and ‘previously untreated’ patients were both included to allow the costing of the complete patient pathway from time of diagnosis. It is worth noting that the newly diagnosed criterion only applied to induction therapy studies.

For studies focusing on consolidation therapy, complications of treatment, and supportive or palliative care, the newly diagnosed criteria was not applied, as it is not necessary to restrict with the newly diagnosed and previous untreated criteria.

c. Age

All the relevant economic evaluation studies on AML/APML were included regardless of the age of the study patients. The reason for not taking age into consideration was that AML/APML can occur in the young and the elderly groups [52, 53].

2.2.2 Intervention and comparisons

All AML/APML studies involving cost calculations were included. The reason for this was to reveal how the costing methods were carried out in previous studies. This included cost analysis, cost utility analysis, and cost effectiveness analysis. However, clinic management studies were not included as these studies were not related to cost estimation.

Also, previous ‘review studies’ were excluded. The reason for this was that ‘review studies’ could not provide information related with the costing methodology, as these studies mainly focused on summarizing the cost results of other original studies. It is worth noting that the economic evaluations for single intervention or for comparison of multiple interventions were all included. The interventions were further categorized at later stages of the review.

2.2.3 Outcome

For the purposes of the current review, the primary outcomes were costing methods and costing details, while the secondary outcomes were cost results.

a. For the objectives of the current review, costing methods and costing details (such as data sources and associated cost drivers) reported in previous studies were regarded as the primary outcomes. These details provided useful references for the costing method that was used at later stages of the current study.

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b. Cost results were set as the secondary outcome of the current review. Through the transformation of the cost values to 2007 USD, cost results from studies from different countries, or those using different methods became comparable. The reason for converting currencies to US dollars, and not the opposite, was that most of the cost-study results were published in US dollars.

2.2.4 Language

Only relevant studies written in English were included in the current review. This was for 2 reasons. Firstly, as English journals are a central point of the field in the present day, papers published in them are guaranteed to have been subjected to thorough reviewing.

Therefore, papers written in English are considered to be of a higher quality standard than papers written in other languages [54]. Secondly, in most cases articles from non-English journals were very difficult to access/obtain, in contrast to study abstracts written in English that could be easily obtained through the main search engines of electronic databases for health care studies (such as MEDLINE, PUBMED, EMBASE). However, excluding non-English papers might cause language bias. Previous studies have shown that research reporting effective interventions is more likely to be published in English [55-57]. Therefore, it was expected that the costing methods and results for ineffective intervention could be overlooked in the current review.

2.2.5 Publication status

Unpublished studies were considered to be of a lower quality standard than published ones (as they are likely not to have been reviewed thoroughly) and, thus, could bias the review results. However, both published and unpublished studies were included in the current review. This was mainly for two reasons. Firstly, excluding unpublished studies would cause publication bias, which effectively means that studies with significant findings are more likely to be published [58-62]. Therefore, excluding the unpublished studies could bias the results of the current review. Secondly, including the unpublished studies increased the amount of the reviewed studies. Therefore, it was considered that the inclusion of both published and unpublished studies would help in collecting as many relevant studies as possible, while it would also prevent publication bias.

2.2.6 Year of publication

In order to include as many relevant studies as possible, no restriction on the year of publication was generally desirable in the current context. However, only studies

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published between 1995 and 2008 were included here. This was for 3 reasons. Firstly, most of the available studies were published after 1994. Secondly, cancer treatments advanced rapidly. Treatments used before 1994 were not applicable in the present day.

Thirdly, the Calman Hine Report (1995) introduced into the reconfiguration of cancer services in 1995 in order to ensure the quality of cancer services [63]. Therefore, it was decided the cut-off point of the year of publication to be set to 1995.

2.2.7 Full text versus abstract

Ideally, only full report studies should be included. However, due to the difficulty of full text access, abstracts were also included if they had sufficient relevant PICO information (population, intervention, control, and outcome). This ensured that the highest possible number of studies was identified.

2.3 Study selection 1 (search strategies)

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In document CANCER TREATMENT PATHWAYS: AML A DETAILED COSTING STUDY EXAMPLE HAN-I WANG. PhD (Page 38-42)