Sexuality is an important part of life for many individuals. Chronic back pain has been shown to have negative consequences on sexual function, which can contribute to a deterioration in quality of life.1–4 Previous studies have evaluated sexual function in patients with chronic pain, cardiac disease, rheumatic conditions, and hip arthritis,2,5,6 and some have evaluated sexual function in patients undergoing spinal surgery.1,7–9 These studies show that sexual function is generally improved postoperatively when compared to preoperative function. However, these studies were comprised of a small sample size, lacked a nonoperative control group, and focused on intervertebral disk herniation,1 total disk replacement,7 anterior spinal surgery,8 and thoracolumbar fusion to the pelvis.9
The benefits of nonoperative versus operative treatment for patients with spinal stenosis (SPS), and degenerative spondylolisthesis (DS) with regards to sexual function are unknown. Moreover, it is unknown whether or not sexual function is important for patients with spinal pathology and low back pain, including DS and SPS.
This study aims to first determine whether sexual function is relevant for patients with SPS and DS and to identify patient characteristics associated with an increased relevance of sexual function. We hypothesize that marital status and age are relevant to sexual function in patients with DS and SPS.
The second specific aim of the study is to determine the impact of operative intervention on sexual function for patients with DS and SPS. We hypothesize that surgical intervention and pain are important predictors of sexual function in patients with DS and SPS.
MATERIALS AND METHODS
The SPORT study and cohort have been previously described.10 Preoperative demographics, comorbidities and clinical diagnoses, and treatment including nonoperative and operative including the number of levels fused were obtained on patients enrolled in the SPORT study. Postoperative and follow-up information was also collected, which included a modified version of the Oswestry Disability Index (ODI).
The ODI was developed by Fairbank et al11 to evaluate functional difficulties related to everyday activities such as getting dressed, lifting, walking and running, and sleeping. Question number 9 of the modified ODI used in SPORT asks, “In the past week, how has pain affected your sex life?” The response options are: My sex life is unchanged; My sex life is unchanged but causes some pain; My sex life is nearly unchanged, but it is very painful; My sex life is severely restricted by pain; My sex life is nearly absent because of pain; Pain prevents any sex life at all; Unable to answer or does not apply to me. Patients were asked to complete the ODI upon enrollment (baseline) and at 6 weeks, 3 months, 6 months, and 1, 2, 3, and 4 years of follow-up. The response rates for all patients enrolled in the study for each question and response option for the ODI were tabulated. The response rates to question number 9 regarding sexual function were compared to the response rates to the other questions (1–8). Specifically, the number of times the patients left the answer blank or selected response option 7, “Unable to answer or does not apply to me” was calculated. The patients who selected this response or did not respond at all were grouped and classified in to the sexual life not relevant (NR) group. Specifically, relevance in this study is used and is synonymous with “applicability” as stated in the ODI. Patients who responded to question number 9 with response options 1 to 6 were classified into a sexual life relevant (SLR) group.
Baseline demographic characteristics, comorbidities, and health status measures were compared between the NR and SLR groups using χ2 tests for categorical variables and t tests for continuous variables. Logistic regression was used to explore factors influencing sexual life not relevant (NR) after adjusting for other variables in the model. Variables that were significant at P < 0.10 were candidates for inclusion in the final multivariable model. Final selection for the model was done using the stepwise method as implemented in SAS 9.2 (SAS Institute, Cary, NC), which sequentially enters the most significant variable with P < 0.10 and then after each entered variable removes variables that do not maintain significance at P < 0.05. Variables considered for entry into the model were listed in Table 1 except “ethnicity” and “listhesis level.” These were excluded because majority of patients are non-Hispanic, and “listhesis level” is only available for DS patients and missing for all SPS patients.
The three operative treatment groups (surgery without fusion, one level fusion, and two or more level fusion) were compared to the nonoperative group with regards to response to ODI question #9 to determine the impact of surgery on sexual function. Nonoperative treatment in this cohort is well described in SPORT trial.10 Patients for whom sex life was not relevant were excluded from this analysis. Baseline demographic characteristics, comorbidities, and health status measures of the four treatment groups were compared using χ2 tests for categorical variables and analysis of variance for continuous variables.
Because of the crossover between the nonoperative and operative treatment arms, analysis was based on treatments actually received in the combined randomized and observational cohorts. In the as-treated analysis, the treatment indicator was a time-varying covariate, allowing for variable times of surgery. Times are measured from the beginning of treatment, that is, the time of surgery for the surgical group and the time of enrollment for the nonoperative group. Therefore, outcome measures before surgery were included in the estimates of the nonoperative treatment effect. After surgery, outcome measures were assigned to the surgical group (based on what type of surgery was performed) with follow-up measured from the date of surgery.
Patients that responded with options indicated having sex life-related pain. The percentage of patients who reported having sex life-related pain was compared across time and across treatment groups (three operative groups and a nonoperative group). In detail, the repeated measures of pain with sex life (having sex life-related pain vs. sex life unchanged), a binary outcome, were analyzed via a longitudinal model based on generalized estimating equations (GEEs) with logit link function. The analysis was adjusted for age, sex, race, diagnosis, marital status, depression, baseline stenosis bothersomeness, and baseline pain with sex life. Outcomes between treatment groups at each time point were compared using a Wald test. Across the 4 years of follow-up, overall comparisons of the “area under the curve” between groups were made by using a Wald test. Computation was done using SAS procedure PROC GLIMMIX. Statistical significance was defined as P < 0.05 based on a two-sided hypothesis test with no adjustments made for multiple comparisons.
Relevance of Sex Life to SPS and DS Patients
A total of 1235 patients were included to determine relevance of sex life. Three hundred sixty-six (29%) of those patients did not answer (n = 12) or responded with response option 7, “Unable to answer or does not apply to me” (n = 354) were included in the NR group. 869 patients selected choices 1 to 6 for the sex life question and were included in the SLR group. At baseline, 481 patients (55% of SLR group, 39% of all patients) reported having some level of pain associated with their sex life, whereas 388 (45% of SLR group, 31% of all patients) reported having no pain with their sex life.
Table 1 shows the results of univariate analysis comparing the SLR and NR groups with regards to baseline demographic characteristics, comorbidities, and health status measures. Table 2 shows results from the multivariable model exploring factors influencing the response of NR. The SLR group was younger than the NR group (63.4 vs. 69.7, P < 0.001). Patients that were older, female, unmarried, had three or more stenotic levels, and had central stenosis were more likely to be included in the NR group.
Operative versus Nonoperative Treatment and Sex Life
Of the 869 patients in the SLR group, 825 had at least one follow-up through 4 years. Forty-four patients were excluded as they did not have follow-up data on the sex question, leaving 825 patients that were included in the analysis comparing operative versus nonoperative treatment. Four hundred forty-nine of these patients had SPS, whereas 376 had DS. Two hundred ninety-four patients underwent nonoperative management. Five hundred thirty-one underwent operative management; 270, 192, and 69 patients received decompression alone, one level fusion, or more than one level fusion, respectively.10 Baseline demographic characteristics, comorbidities, and health status measures according to treatments received are shown in Table 3 .
Table 4 and Figure 1 show the percentage of patients in each treatment group reporting pain related to sex life through 4 years of follow-up. The percentage of patients experiencing pain with sex life was higher for the operative treatment groups (although not statistically different) compared to the nonoperative group at baseline. At all follow-up time points, the three operative groups had a lower percentage of patients reporting pain with their sex life compared to the nonoperative group (P < 0.05 at all time points except between two or more level fusion and nonoperative at 4 years of follow -up).
This study assessed sex life function responses to patients with SPS and DS using responses to the ODI and whether the sex life function question was applicable (relevant) to patients with these conditions. The findings demonstrate that at baseline, sex life was relevant to the majority of patients (71%) and 55% of these (39% of all patients) had some pain affecting their sex life. This is similar to previously reported rates of pain affecting sex life in patients with low back pain.7–9 Given the high rate of patients whose sex life is affected by pain, it is an appropriate issue for the physician to address with their patient. Previous studies show that only 41% of physicians routinely question patients with lumbar disc herniation about sexual problems.1 One reason for this may be because of the fact that surgeons are unaware of the importance of sex life for patients. The information presented here suggests that sex life function is relevant to patients with spinal pathology and should be addressed. The study did identify a subset of patients for which sex life was less likely to be applicable: patients who were older, female and unmarried, and with coexisting joint problems or hypertension.
The impact of operative intervention on improvement in pain related to sexual activity was also assessed. At baseline, the operative groups had a higher percentage of patients with pain related to sexual activity compared to the nonoperative control group. Figure 1 shows a drastic treatment effect of surgery by 3 months after surgery and improvement in pain related to sex. The number of patients in operative group reporting pain with sexual activity decreased to below 20% and remained in this range throughout 4 years of follow-up. In contrast, approximately 40% of patients in the nonoperative group reported having some level of pain with sexual activity throughout the follow up period. These findings are similar to previously published reports. Berg et al7 showed that sex life improved significantly with a decrease in low back pain after posterior lumbar fusion and total disk replacement. Hamilton et al9 showed that 40% of older patients with thoracolumbar fusion to the pelvis had no or only mild sexual dysfunction. In contrast to previously published reports, this is the first study to include a large number of patients and include a nonoperative control group.
There are a number of limitations to the study, most notably; pain with sex life was determined using one question from the ODI. The validity of the study would have been improved by using a validated survey that more comprehensively addresses sexual function and is able to assess differences across time. The method of assessing pain also did not account for different severity of pain. Nonetheless, the study does show that fewer patients report having pain related to sexual activity following operative management of DS and SPS compared to nonoperative treatment. The duration of the effect may be limited by several factors including development of adjacent level pathology. Further studies are ongoing to better characterize improvements in sexual function and activity following operative treatment for DS and SPS. Another notable limitation is that a secondary analysis of the SPORT data was used and not all patients were tracked at each follow-up time point. Finally, to determine whether or not sex life is applicable or not, it was assumed that sex life was not applicable for those that did not respond or selected, “Unable to answer or does not apply to me.” This is a reasonable assumption to make, but the question does not definitively ask patients whether they are involved in sexual activity or how important their sex life is and this supports the design of a prospective study to better understand spine-related variables affecting this fundamental function of life. Nonetheless, the findings suggest that sex life questions are less applicable for older, female, and unmarried patients and patients with coexisting joint problems.
Sex life is a relevant consideration for 70% of patients enrolled in the SPORT study with DS and SPS. Older, female, and unmarried patients and patients with coexisting joint problems or hypertension were more likely to state that sex life did not apply to them. Compared to the nonoperative treatment group, fewer patients in the operative group reported pain related to their sex life. Sex life is a relevant consideration for the majority of patients with DS and SPS; operative treatment leads to improved sex life-related pain.
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Keywords:Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
degenerative spondylolisthesis; sex life related pain; spinal stenosis; SPORT study