What was the sampling technique used and what are the advantages and disadvantages of using that technique? The researchers used a two-stage sampling method that was non-random in the first stage and randomized in the second stage. The total population was made up of 137 patients who were admitted for preterm labour. Selection from this initial population was non-random because there were exclusion criteria. The seventy women included were randomised to their treatment groups by assigning randomly generated numbers.
The main advantage of using the technique was its simplicity and straightforwardness. Every individual who fit the inclusion criteria had equal chance of being selected. The disadvantage of the technique was that there was bias in the initial selection. Such bias could have affected the accuracy of the experiment. Was there randomisation? There was randomisation in the second stage of sampling, where all those women who fit the inclusion criteria were part of the sampling population. Randomisation was done by generating random numbers and assigning numbers to the women included in the study.
Was it biased? There were several sources of bias in the study. The fact that the patients were all from the same clinic is already in itself introducing bias. The study was not double blind, which could also be a source of bias. The use of exclusion criteria in the first stage of sampling lessened the bias. In the second stage of sampling, efforts were done to further remove bias by assigning treatment to all included patients. No patient also left the study, thus further reducing bias. Describe the validity and power of the study
Based on the researchers’ desired results, the statistical power of the study for improving latency was initially calculated be 80% with an assumption of getting standard deviation (SD) of 12 days at 5% level of significance. However, when their results came out, the power was calculated to be lower (value for this was not presented in the paper). By checking the means and SD for latency, and assuming a two-tailed analysis, power was calculated to be 51% only. This could be attributed to the high standard deviation that could in turn be due to the relatively small number of samples tested.
In other similar studies, the sample population is much higher. For example, another study testing the effect of vaginal progesterone on preterm birth used 413 women (Eduardo B. Da Fonseca, et al. , 2007). Despite the low statistical power, the results presented here are valid as preliminary data on the supplementation of tocolytic therapy with vaginal progesterone to control preterm labour. The study was able to show that progesterone treatment had an effect on the other outcomes that were measured (please refer to Table 2 in the text).
Background information of the hypothesis Progesterone is a steroid hormone that is widely used in hormone replacement therapy in menopausal women. It is also used to induce menstruation in women who suddenly stop menstruating. Its capacity to control preterm labour was first reported in the 1980s. Oral administration of progesterone induces side effects like migraine, dizziness, vomiting and blurred vision. This was the usual mode of administration of progesterone, which was proven effective to reduce preterm labour (Meis, et al. , 2003).
Since 2003, studies have reported on the use of progesterone vaginal suppository to treat preterm labour (E. B. Da Fonseca, Bittar, Carvalho, & Zugaib, 2003) and even in high risk women (Eduardo B. Da Fonseca, et al. , 2007). Until this current study, there were no previous reports on the use of progesterone to supplement tocolytic therapy, using magnesium sulphate and intravenous ampicillin, on women who actually had preterm labour. Hypothesis of the study Null hypothesis: The use of vaginal progesterone after inhibition of preterm labour will not change latency period and recurrence of preterm labour.
Alternate hypothesis (what the study really wants to prove): After the inhibition of preterm labour, treatment with vaginal progesterone will result in increased latency period and decreased recurrence of preterm labour. Methodology The study was conducted on 70 women who were had arrested uterine activity after they were treated for premature labour. The women were randomized to two groups; one was administered vaginal progesterone and the other, a placebo, until delivery. Subjects were monitored for days to latency until delivery, recurring preterm labour and other primary and secondary outcomes.
Different statistical tests were used to determine if the treatments resulted in significantly different outcomes. Comparisons were done using Student’s t-test for quantitative data; chi-square and Fisher exact tests, among others, were used for categorical data. Conclusion of the study The study concluded that the use of vaginal progesterone after tocolytic therapy was effective in increasing latency to delivery but not in decreasing the incidence of recurrence of preterm labour. Is it a valid assumption based on the data of the study? Describe the applicability and relevance of the paper to clinical practice.
The conclusion is valid based on the data of the study. The paper and the results presented are applicable and relevant to clinical practice because it proposes a new means of treating preterm labour for increased latency. Although the recurrence of preterm labour appeared not to be reduced with the treatment, this could be due to the advanced stage of the pregnancy when the preterm labour occurred or due to the small sampling population. It is significant to note that this is the first to report on the supplementation of tocolytic therapy with vaginal progesterone. Further studies can also be done to validate the results.