Pelvic organ prolapse (POP) surgery among Danish ...

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Sep 3, 2014 - posterior wall and the rectovaginal fascia. This study highlights a need for further large studies to fully explain the epidemiology of POP after ...
Int Urogynecol J (2015) 26:527–532 DOI 10.1007/s00192-014-2490-y

ORIGINAL ARTICLE

Pelvic organ prolapse (POP) surgery among Danish women hysterectomized for benign conditions: age at hysterectomy, age at subsequent POP operation, and risk of POP after hysterectomy Rune Lykke & Jan Blaakær & Bent Ottesen & Helga Gimbel

Received: 26 April 2014 / Accepted: 13 August 2014 / Published online: 3 September 2014 # The International Urogynecological Association 2014

Abstract Introduction and hypothesis The aim of this study was to describe the incidence of pelvic organ prolapse (POP) surgery after hysterectomy from 1977 to 2009, the time interval from hysterectomy to POP surgery, and age characteristics of women undergoing POP surgery after hysterectomy and to estimate the risk of undergoing POP surgery after hysterectomy. Methods The study was a population-based registry study. Patient data from 154,882 women hysterectomized for benign conditions in the period from 1977 to 2009 were extracted from the Danish National Patient Registry. Patients were followed up from hysterectomy to POP surgery, death/emigration, or end of study period. An estimate of the hazard of undergoing POP surgery following hysterectomy was calculated. Survival analysis was performed using the Kaplan-Meier product limit method. Results The frequency of POP surgery on hysterectomized women was high the first 2 years of the follow-up period with almost 800 women operated yearly. More than one third (n= 2,872) of all women operated for POP were operated less than 5 years after the hysterectomy with a median of 8.6 years. The cumulated incidence of POP surgery after hysterectomy with follow-up of up to 32 years was 12 %; 50 % (n=5,451) of all POP surgeries were in the posterior compartment. The mean age of women undergoing a first POP surgery after hysterectomy was 60 years. R. Lykke (*) : J. Blaakær Department of Obstetrics and Gynecology, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark e-mail: [email protected] B. Ottesen Juliane Marie Centre, Rigshospitalet, Copenhagen, Denmark H. Gimbel Department of Obstetrics and Gynecology, Nykøbing Falster Hospital, Nykøbing, Denmark

Conclusions POP after hysterectomy occurs as a long-term complication of hysterectomy; 12 % of hysterectomized women were operated for POP. They were operated at younger age than non-hysterectomized women and half the POP operations were performed in the posterior compartment. Keywords Hysterectomy . Pelvic organ prolapse . Urogynecology . Hazard rate . Kaplan-Meier Abbreviations POP Pelvic organ prolapse

Introduction Hysterectomy and pelvic organ prolapse (POP) surgery are two of the most common operations for benign gynecological conditions [1]. The frequency of hysterectomy for benign indications in Denmark has been stable at around 180 hysterectomies/100,000 women per year from 1977 to 2011 [2]. The incidence of POP surgeries was 201/100,000 women in 2008. The incidence of women undergoing POP surgery was 146/ 100,000 women during the same year [15]. Hysterectomy has generally been considered a treatment for POP in cases with prolapse of the apical compartment. In recent years, however, it has been suggested that hysterectomy is also a risk factor for POP [3]. So far there has not been much consensus regarding the epidemiology of this. A Swedish case-control study [3] found an increased risk of POP surgery among hysterectomized women compared with nonhysterectomized controls. The risk of having a prolapse after hysterectomy was highest in the initial 5 years after hysterectomy. An American study [4] found a median duration between hysterectomy and POP surgery of 13 years. Another Swedish study [5] found that women undergoing vaginal vault prolapse surgery were significantly younger at

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the time of hysterectomy than women who did not undergo POP surgery. Other studies [6–8] have not found such an association. The aim of this Danish study was to describe the incidence of POP surgery after hysterectomy from 1977 to 2009, the time interval from hysterectomy to POP surgery, age at hysterectomy of those women who had a subsequent POP operation, and the age of women undergoing POP surgery after hysterectomy and to estimate the risk of undergoing POP surgery after hysterectomy.

Materials and methods The Danish National Patient Registry holds information about all hospital admissions and surgical procedures from all public and private hospitals in Denmark [9]. We collected data on all benign hysterectomies (n=168,474) and POP surgeries performed in Denmark on Danish women from 1 January 1977 to 31 December 2009. The classification of diagnoses was changed in 1994 and the classification for surgery was changed in 1996. The International Classification of Diseases, Eighth Revision (ICD-8) was used from 1 January 1977 to 31 December 1993, while the ICD-10 (Tenth Revision) was used from 1 January 1994 to 31 December 2009. The old Nordic classification for surgery was used from 1 January 1977 until 31 December 1995 and the new Nordic classification was used from 1 January 1996 until 31

December 2009. Table 1 shows the operation codes included in the data set. For each patient, the personal identification number, discharge diagnosis, admission and discharge dates, date of death or emigration, and hospital codes were collected. Women with POP surgery preceding the hysterectomy were excluded (n= 13,592); hence, the study cohort consisted of 154,882 hysterectomized women with no prior POP surgery recorded. All POP surgeries were classified into four groups according to the compartment affected (Table 1): anterior compartment, apical compartment, posterior compartment, and unclassified. The unclassified operations were procedures we could not clearly classify into one of the three compartments such as colpopexy. Operation codes for these procedures were introduced with ICD-10 in 1996. Only the first incidence of POP surgery after hysterectomy was included for analysis in this study. Stata 12.1 (StataCorp, College Station,TX, USA) was used for data analyses. For normally distributed continuous data mean ± standard deviation (SD) was reported, and for nonnormally distributed data median and interquartile range was reported. Follow-up time was defined as date of hysterectomy to first POP surgery, death/emigration, or end of study period (31 December 2009). The instantaneous hazard rate was estimated as described in the Encyclopedia of Biostatistics [10]. The Kaplan-Meier curve was constructed using techniques previously described [11]. The study was approved by the Danish Data Protection Agency (reg. no. 2010-41-4286).

Table 1 Operation codes collected from the Danish National Patient Registry

Hysterectomy procedures Abdominal hysterectomy Cesarean section and total hysterectomy Supravaginal hysterectomy Vaginal hysterectomy Vaginal supravaginal hysterectomy Colpoperineoplasty and vaginal hysterectomy Total laparoscopic hysterectomy Laparoscopic hysterectomy Laparoscopically assisted vaginal hysterectomy POP procedures

Compartment

Anterior colporrhaphy Manchester operation Posterior colporrhaphy Vault suspension Vaginal enterocele repair Colpocleises Colpopexy (lateral) Other abdominal and laparoscopic operations for POP

Anterior Anterior/apical Posterior Apical Posterior Apical Unclassified Unclassified

Old Nordic classification (1977–1995)

New Nordic classification (1996–2009)

61020

KLCD00 KMCA33 KLCC10 KLCD10 KLCC20 KLEF13 KLCD01 KLCD04, 97 KLCD11

61000 61040

61050 62200 62300 62220 & 62240 62140 62420 & 62400 & 74660 62340

KLEF00(A) KLEF00B KLEF03(A), 10 KLEF50(A), 51(A), 53(A/B) KLEF40(A), 41(A), 43(A) KLEF20, 23 KLEF60, 63, 64 KLEF96, 97

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Results From 1977 to 2009, 154,882 women had a hysterectomy performed for benign indications; these women were the study cohort. A total of 13,274 POP surgeries were performed on 8,281 women after hysterectomy; 6,805 women were operated for POP once after hysterectomy (in one or more compartments) and 1,476 women twice or more (Fig. 1). The total follow-up time was 2,290,751 years, which yields an overall rate of POP surgery after hysterectomy at 362/100,000 person years (8,281 women/2,290,751 years). The mean follow-up time was 14.8 years (±9.3). The median interval between hysterectomy and first POP surgery was 8.6 years (3.1–15.9). Fig. 1 Flowchart of patients in the study

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For women undergoing their first POP surgery after hysterectomy, we calculated their age at hysterectomy. The median age was 48 years (43–55). For all women in the cohort, the median age was 46 years (41–51) at hysterectomy. The mean age of women undergoing a first POP surgery after hysterectomy was 60 years (±10.6). The number of POP surgeries after hysterectomy was high the first 2 years after hysterectomy with almost 800 women operated yearly (Fig. 2). Some women had surgery in more than one compartment so the total number of surgeries was higher than the number of women. The number of POP in the posterior compartment was higher than that of the anterior, apical, and unclassified throughout the study period, although after 20 years

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Fig. 2 Number of POP surgeries and number of women operated for POP following hysterectomy for each year after hysterectomy

follow-up it tended to level out with the anterior compartment; 50 % (n=5,451) of all POP surgeries were in the posterior compartment, and 35 % (n=2,872) of women operated for POP were operated within the first 5 years after hysterectomy. Figure 3 depicts the smoothed hazard rate estimate (instantaneous hazard) which are the increments of the cumulative Kaplan-Meier plot. There appeared to be an increased hazard of undergoing POP surgery the first 2 years after hysterectomy up to 0.4 %, which decreased to 0.3 % at 7 years. Figure 3 further depicts an increase in the risk of undergoing POP surgery from 7 years up to 25 years after hysterectomy with a plateau at 12–15 years. At 25 years the hazard rate was highest at around 4.25‰. When plotting the hazard on a Kaplan-Meier plot (Fig. 4), a slightly steeper slope the first 2 years reflects the increased hazard seen in the first years after

hysterectomy (Fig. 3). The increase seen from 7 to 25 years is not clearly reflected due to the lower number of persons at risk. At the end of the study period (32 years), the cumulative incidence was 12 %.

Fig. 3 Smoothed estimate of the hazard of undergoing POP surgery after hysterectomy

Fig. 4 Kaplan-Meier plot showing the cumulative hazard of undergoing POP surgery after hysterectomy

Discussion Our study showed that median age at hysterectomy was 48 years for women undergoing a first POP surgery after hysterectomy and that the mean age at first POP surgery was 60 years. The frequency of POP surgery on hysterectomized women was high the first 2 years of the follow-up period. It showed that more than one third of all women were operated less than 5 years after the hysterectomy, with a median of

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8.6 years. When calculating the hazard rate estimate, the risk of POP surgery was confirmed to be high the first 2 years after hysterectomy, but an increase in hazard rate was also seen from 7 to 25 years after hysterectomy. At 25 years the hazard rate was highest at around 4.25‰. The cumulative incidence 32 years after hysterectomy was 12 %. In large cohort studies such as this, it is of great importance that data collected from registries are validated and suitable for analysis. The Danish National Patient Registry has previously been studied [9] and found suitable for epidemiological studies. Specifically the validity of POP surgery registration and reporting has been studied [12] and found satisfactory. The size of the cohort, which is only equaled by a few other studies from Scandinavian countries, along with the quality of the data, is an advantage of this study. To our knowledge, no other studies have described the frequency of post-hysterectomy POP surgery in a cohort through an extended study period. The study had several limitations. We excluded women with POP surgery prior to hysterectomy, but as there were no data before 1977 we cannot be sure if some women in the study had POP surgery performed before the hysterectomy during the years before 1977. Also, we cannot be sure if some women in the study had a preexisting POP before hysterectomy and that the hysterectomy worsened the condition. Further, due to different follow-up times, POP after new operation methods for hysterectomy (for example, laparoscopic techniques) implemented late in the study period might not be reflected properly. We included only women operated for POP. The true incidence of POP is probably higher; some women never seek medical assistance for their POP, and some women respond well to conservative treatment (e.g., local hormones, pelvic floor exercises, pessary) [13] and never undergo surgery. We found a mean age of 60 years for women undergoing a first POP surgery after hysterectomy. Our results indicate that hysterectomized women in general undergo POP surgery 10 years earlier than non-hysterectomized women in the Danish population that was studied [14]. This finding could be interpreted in the way that hysterectomy accelerates the development of POP or might even be the cause of POP. We found a high frequency of POP surgeries the first 2 years after hysterectomy. With 35 % of women operated for POP within the first 5 years after hysterectomy and the initial high hazard we reported, our results are in concordance with the results of a Swedish study [3]: this study concluded that the highest risk for prolapse surgery was during the initial 5 years after hysterectomy. This result supports our interpretation of the finding that hysterectomy might accelerate the development of POP. We would expect women to be more concerned about POP symptoms after gynecological surgery as this may be conceived as complications. This might explain the high frequency of POP surgery the first 2 years after hysterectomy. In the past a follow-up visit after hysterectomy was normally

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conducted. At these visits POP might have been discovered, which might also explain the high frequency the first 2 years. We found a median interval between hysterectomy and first POP surgery of 8.6 years, which is shorter than the 13 years reported in an American study [4]. Other studies report a mean interval of 6.2 years [15] and 13.7 years [5] for vaginal vault prolapse. Direct comparison cannot be made, as our median value was for all types of POP surgery, while the other studies focused on vaginal vault prolapse. It seems clear, however, that POP after hysterectomy is a condition, which can occur a few years after the hysterectomy. The cumulative incidence of POP surgery after hysterectomy was 12 % in this study, which is higher than the 5.1 % reported in an American study [8]. The study period was 32 years in our study as compared to 30 years in the American study. This, however, cannot explain the difference, as the cumulative incidence at 30 years was around 10 % in our study. In our study the follow-up included operations in all hospitals in Denmark and were not limited to one region. Hence, the risk of women undergoing POP surgery in a different region and thereby not being registered is not present in our study, whereas it might have been the case in the American study. Another American study found a lifetime risk of undergoing POP or incontinence surgery of 11.1 % [16], whereas a new Danish study [14] found the lifetime risk of only POP surgery was 18.7 %. The reason for the difference in the studies could be that the development of POP is higher in our population in general, that is the pelvic floor and supportive tissue are weaker, or that a larger number of women were treated conservatively in the American study. The results of this study imply that POP could be taken into consideration as a long-term complication of hysterectomy when advising women about treatment and that POP becomes symptomatic during the first 5 years post-hysterectomy. Further, it implies that special care should be taken to suspend the vaginal vault properly at hysterectomy—especially the posterior wall and the rectovaginal fascia. This study highlights a need for further large studies to fully explain the epidemiology of POP after hysterectomy. We suggest studies with special focus on the risk of POP surgery related to the different methods of hysterectomy and indication for hysterectomy.

Conflicts of interest None.

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