Zirconium Metal‐Organic Frameworks
1.3. Results and Discussion
The design of the pilot study replicated previous studies‟ design (see Chp. 2;
Section 2.2, p.35), as it used retrospective data from notes and frequency-matched 2 controls for each subject. It was a retrospective case control design (Bowling 2009), with information from women‟s obstetric notes and colposcopy database.
This choice reflected the pragmatic stance of the author but the design varied from the design of previous studies, in that it planned at the outset to examine and analyse the data by parity groups (how many babies women had before the birth).
This was one of the limitations identified in most of the previous studies, that although all mentioned including women of all parities in their studies, because of the difference parity makes to the woman‟s labour, none of the studies had analysed by parity. This pilot study was the first step in addressing this omission.
Chapter 3 Pilot study
Another limitation of previous studies was the lack of definition of the 1st stage of labour and the point from which calculations were based. The pilot study established a point at which the measurement of time in the 1st stage was taken. As 1st stage was commonly divided into „passive‟ and „progressive‟ stages and previous studies did not identify if they were using total length of both parts in their measurement of 1st stage, or the dilatation from which their measurements started, the pilot study rectified this and defined both these points. This type of design is discussed more fully in the methodology section of Chp. 4; Section 4.4, p.89.
3.3.1 Sample
The sample was taken from the population of all women living in the North East who delivered at the study hospital in 2001. For feasibility by a lone researcher, it had to be placed in one locality. This did not preclude the results being applicable to the general population of women who had a baby after LETZ, as the catchment area of this hospital included representation from most social groupings. Delivery data were taken from the obstetric notes of women who had given birth in this hospital in 2001.
The notes of women who had LETZ before giving birth were accessed and 2
matched controls identified for each of these women. Control women were matched for age (plus or minus 3 years) and parity at delivery. All were women who gave birth in 2001. All were women who gave birth after 24 weeks gestation. The decision to allocate two controls to each subject woman was to accommodate the range of analgesia options, as these have known effects on progress in labour (Wagner 1996b; Howell, Kidd et al. 2001). It also meant that analgesia options were less likely to confound the variables under study. Statistical advice resulted in the target figures of 30 subject women and 60 control women agreed as being a sample size that would answer the pilot study questions.
Women‟s details were accessed from the computerised database of all women who delivered in 2001. This enabled the identification of subject women who had LETZ and control women who did not, prior to accessing their notes and prior to accessing subject women‟s LETZ details from the colposcopy database. The colposcopy database was started in 1997; therefore, it was necessary that subject women had their LETZ after that time. In order to access consistent colposcopy data, as well as
Chapter 3 Pilot study
limiting to one locality, only subject women who had their LETZ at the same hospital as the one they gave birth in were chosen.
Time constraints limited the randomisation of subjects and controls; therefore it was a convenience sample that was used (Creswell 2003). Subject women were
identified from the computerised database, and then sorted by hospital number. This unique hospital number was allocated to each person on first attendance at hospital for an inpatient or outpatient episode. Therefore listing the women by the number gave a random list. This list was searched in numerical order, until both LETZ and obstetric notes were found in medical records for that subject woman. All available notes were used for the subject women.
Having determined which women in 2001 had no LETZ before the birth; they were first stratified by parity, and then sorted by date of birth. The notes for each control woman were accessed from medical records by taking the 1st date of birth, then the last, then the 2nd, then the 2nd last etc. for each parity group until two control women were allocated to each subject woman. As a quality control check, the first 10 sets of medical notes of control women were also inspected, to ensure that the data in the computerised system was correct and to confirm they had not had LETZ. As all the records were correct it appeared reasonable to no longer ensure both sets of notes were available for the control women.
3.3.2 Ethical considerations
Ethical approval was granted for the pilot study, as part of the ethical permissions granted for the main study. Access to data was already available for research in the study hospital and all women attending for birth or treatment at this teaching hospital were aware that data pertaining to their treatment might be used for research
purposes. Despite this, ethical considerations were made, ensuring that no
identifying features of the data were included in the dataset used for analysis. (See Appendix B, p. 263 for copies of ethical permissions).
3.3.3 Data Collection
When the LETZ data in the medical notes were examined, several of the notes were incomplete. The medical notes were paper filed and often the colposcopy details had been lost, mislaid or entered in a non-standard format. The colposcopy
Chapter 3 Pilot study
practitioners at the hospital had also judged the quality of the colposcopy data in the notes as poor. Therefore, in 1997, a colposcopy database was started for the input of all details, which enabled colposcopy audit to be undertaken and robust statistics to be sent to the national colposcopy register. This database was used to extract the colposcopy data for women in the study.
The data was collected using standardised data collection forms for biographical details; colposcopy details; and delivery details, ensuring consistency (See
Appendix C; D and E, p.270-273). The delivery data were taken from the details on the partogrammes in the women‟s notes. Details of LETZ were taken from the colposcopy database. These details were also transcribed onto a standard data sheet. In order to ensure consistency in data collected and to pilot data collection forms for the main study, data collection forms were produced. These forms were peer reviewed by colposcopists and midwives respectively, and amended as necessary following their comments.
The data was entered from the standardised data collection forms into the statistical package SPPS 11.0 and cross-checked for accuracy before analysis. The process of data collection evolved to ensure that uniformity of information was collected. The peer review of the data collection forms and the use of the colposcopy database, were to ensure uniformity of data collection. Formal identification and use of the procedural steps in the data collection provided internal validity to the data collection process and enabled confidence in the quality of the data.