Hernia | 2019
Comment to: Ventral hernia recurrence in women of childbearing age: a systematic review and meta-analysis. T. Nouh, F. S. Ali, K. J. Krause, I. Zaimi
Abstract
We read with interest the recent article of Nouh et al. [1]. The authors conducted a systematic review and meta-analysis on ventral hernia recurrence in women of childbearing age, to propose a management strategy. The authors concluded that pregnancy is a risk factor for ventral hernia recurrence, and further, that postponing surgical repair during the childbearing years could be an option to decrease the risk of recurrence. We support this conclusion, although we have some concerns regarding the method of the present meta-analysis. The authors identified studies on ventral hernia repairs in women of childbearing age. Pooling of data led to estimated recurrence rates of 12% and 9% for women who did and did not become pregnant following the repair, respectively. The associated 95% confidence intervals did not overlap, and thus, the authors concluded that pregnancy is a risk factor for recurrence. However, these percentages should be interpreted with caution due to a high risk of immortal time bias. In order for a subject to be considered in the cohort of women with a subsequent pregnancy, she must by definition be recurrence-free from the time of repair until the pregnancy [2]. If she has a hernia recurrence prior to the pregnancy, this cannot be attributed to the pregnancy, and hence, this recurrence is correctly classified to the cohort of women without a subsequent pregnancy. Thus, bias might be introduced if the interval between the initial repair and pregnancy is ignored. This is the case when comparing the above-mentioned recurrence rates, where respective overand under-emphasizing the recurrence risks in the non-pregnant and pregnant cohorts are a major pitfall. An example of this can be found in one of the included studies in the meta-analysis, which reported almost identical recurrence rates of 12.5% and 12.7% for the two groups [3]. However, in an extended multivariable Cox regression analysis, taking the interval from initial repair to pregnancy into account, the study found that a subsequent pregnancy was associated with a nearly 1.6-fold increased recurrence risk (hazard ratio 1.56, 95% CI 1.09–2.25, p = 0.016). Furthermore, interpretation of the crude recurrence rates is difficult, as these were based on pooled data from patients with either primary ventral or incisional hernias [4]. Based on the findings of the study, the authors proposed an algorithm for treating ventral hernias in women of childbearing age. For women considering a future pregnancy, but a ventral hernia affecting quality of life, the authors suggested a laparoscopic repair. This approach, however, is not supported by the literature, in which there is no clear favorable approach for women in the fertile age [5]. Thus, we advocate against recommending one treatment over another when the evidence behind such recommendation is lacking. The sparse literature included in the review of Nouh et al. [1] emphasizes the need for more research in this field.