Benign prostatic hyperplasia (BPH) affects approximately 210 million men globally and is a major cause of lower urinary tract symptoms (LUTSs) in aging men [1]. LUTSs negatively affect patients’ quality of life and cost the US healthcare system more than $4 billion each year [2]. One study estimated that 50% and 75% of men have histological evidence of BPH by the age of 50 and 80 years, respectively, with approximately 50% of them having clinically significant symptoms [3]. The sequelae of BPH include a decreased urinary flow and advancing voiding and storage symptoms; these may eventually result in acute or chronic urinary retention (UR) [4]. Although men with acute UR caused by BPH have an increased chance of returning to normal voiding if treatment with α-1 blockers is started at the time of catheter insertion [5], 24%–42% of patients elect to receive surgical intervention instead [6, 7]. According to the updated guidelines, surgical intervention is an appropriate treatment for patients with moderate-to-severe LUTSs and for patients who have developed acute UR or other BPH-related complications [8]. Surgical treatment is often effective and prevents the need for indwelling or intermittent catheterization in the future [9, 10]. However, in a previous study, 79% of patients received α1-blockers before catheter removal, and most of them could void successfully without requiring an indwelling catheter [11]. To the best of our knowledge, very few studies have compared long-term treatment outcomes between transurethral resection of the prostate (TURP) and medical treatment in patients with BPO who experience UR. Therefore, using data from the National Health Insurance Research Database (NHIRD) of Taiwan, we conducted a nationwide observational cohort study to investigate the surgical outcomes of such patients and compare the long-term treatment outcomes between patients who received medication only and those who underwent surgical intervention.

All clinicians should particularly focus on BPH and BPO, because 50% of men develop pathological BPH at the age of 51–60 years [15]. In the United States, the estimated risk of a 50-year-old man with BPH undergoing therapeutic intervention (surgical or medical treatment) in his lifetime is approximately 40% [16]. A 3-year, multicenter, randomized controlled trial investigated patients with moderate BPH symptoms who were treated through either watchful waiting or TURP. In this trial, 24% and 2.9% of men in the watchful waiting arm crossed over to receive surgical intervention developed UR, respectively [17]. UR, one of the common complications of BPH and BPO, is a distressing urological emergency that seriously affects patients’ health and quality of life. Among men aged 70–79 years with BPH and moderate-to-severe LUTSs (IPSS score > 7), the incidence of UR was determined to be approximately 34.7 per 1000 person-years [18]. Another large-scale study that evaluated an ethnically diverse group of males in the United States reported that the observed incidence of BPH-associated UR increased substantially between 2007 and 2010 [19].

In men with BPH, risk factors for UR include advanced age, severe LUTSs, increased prostate volume, decreased urinary flow rate, and prostate-specific antigen level > 2.5 [20]. Three factors predominate the pathophysiological mechanisms of UR: outflow obstruction, neurological impairment, and an inefficient detrusor muscle [21], among which outflow obstruction is the most common cause [22]. Another urodynamic study on UR reported that outflow obstruction may develop secondary to the interruption of sensory or motor nerve supply to the detrusor muscle, incomplete relaxation of the urinary sphincter mechanism, or inefficient contraction of the bladder detrusor muscle [23].

Once acute UR occurs, the initial management includes immediate decompression of the urinary bladder through urethral Foley catheterization or indwelling suprapubic cystostomy if urethral catheterization is not possible [24–26]. Although UR is one of the absolute indicators for surgical treatment in patients with BPH/BPO [27], TURP is not the first choice of treatment in daily practice because of its potential risks and complications. Instead, α-blockers, which improve BPO in men with LUTSs, are regarded as the first-line treatment for BPO [28]. α-Blockers can result in a successful trial without catheter (TWOC) in patients with acute UR. Some urologists offer a trial of voiding to patients with acute UR, and one study reported that patients voided successfully by 12 weeks after TWOC without surgical treatment [29]. Another study reported that 48% of patients with acute UR had a successful TWOC when they were administered an α-blocker (Tamsulosin), whereas only 26% of patients had a successful trial when no drug was administered [30]. Elsewhere, researchers indicated that after initial catheterization, 72.8% of men had a successful TWOC after a median of 3 days of catheterization, of which 79% had received an α1-blocker (Alfuzosin) before catheter removal [11].

Although treatment with α-blockers without surgical intervention can result in a successful TWOC in patients with acute UR, studies have yet to demonstrate the long-term clinical outcomes of these patients. Therefore, the present study compared long-term clinical outcomes between patients who had received TURP and those who had received medication only by using data from Taiwan’s NHIRD. Before comparing the clinical outcomes of the two cohorts, we performed 1:1 propensity score matching [13] to ensure that the characteristics of the two groups were similar and more objective data could be obtained. Therefore, the distribution of age, incidence of preoperative comorbidities, and Charlson comorbidity index did not differ significantly between the two groups (Table 1).

Moderate-to-severe LUTSs considerably affect all parameters of quality of life for aging men [31], and appropriate management is warranted. TURP is a safe and effective surgical procedure for men with BPH and moderate-to severe LUTSs. TURP can even achieve favorable outcomes in stroke and DM patients with symptomatic benign prostate hyperplasia [32, 33]. All of the patients included in our study had received α-blockers for at least 6 months before experiencing an UR episode. Our results showed that clinical outcomes were more favorable in the TURP group compared with the medication only group, because the TURP group had a lower risk of UTI and UR. Furthermore, the TURP group had a lower incidence of future emergent skeletal fracture during both postoperative 3-year follow-up and life-long observation periods.

Nocturia is not only the leading cause of sleep fragmentation in older adults [34] but also a crucial risk factor for falls among men older than 65 years [35]. A study based on the Japanese National Health Insurance system reported that elderly individuals with nocturia had a higher risk of fracture and death than did those without nocturia [36]. Another study also reported an association of nocturia with a higher risk of comorbidities, such as bone fracture, diabetes, and coronary disease, and thus a higher risk of mortality among elderly individuals [37]. In patients who had experienced acute UR, TURP probably resulted in more favorable treatment outcomes compared with medication alone in terms of LUTSs, including nocturia. LUTSs were relieved once a patient received TURP. TURP appears to reduce the urge and prompt sensation to void and the number of times a patient gets up to visit the toilet at night, thus preventing them from the risk of falls. On the other hand, orthostatic hypotension is an independent risk factor for recurrent falls among the elderly [38]. After receiving TURP, the chance of a patient taking alpha-blockers would probably decrease, thereby reducing the possibility of fall caused by postural hypotension, which is the possible side effect of alpha-blockers.

In this study, we also investigated whether the medication only group had a higher future incidence of urological malignancy. Given that high post-voiding residual urine, repeat UTI, chronic bladder inflammation, and chronic UR all increase the urothelial exposure to carcinogens [39], we hypothesized that the medication only group would have a higher future incidence of bladder urothelial carcinoma. However, our data revealed that the incidence of both bladder urothelial carcinoma and prostate adenocarcinoma was identical in the two cohorts. This may be because the number of patients with malignancy in this study was too small to observe any statistical difference.

This study has some limitations that were inherited from the data structure of the NHIRD. First, this database does not provide detailed personal information, such as laboratory parameters, alcohol consumption, cigarette use, and exercise, which are confounding variables that influence LUTSs and bladder urothelial carcinoma. Some important reports like pre-operative prostate volumes and the urodynamic studies of the patients were not obtained in this study, either. Second, we used strict dichotomy to divide our study population into two groups: the TURP and medication only groups. Thus, we could not assess whether the time length from acute UR to surgery or whether the number of UR episodes affected treatment outcomes. Third, the use of prostatic vaporization (or ablation by laser), which is not reimbursed by the Taiwan NHI, has only become increasingly common in the last decade [40]. Thus, patients receiving prostate laser treatment were not included in this database. However, despite these limitations, this is the first study to compare the long-term treatment outcomes of TURP and medication only for patients who experience acute UR. Thus, we believe this is innovative and valid research.

Although treatment with α-blockers without surgical intervention can result in a successful TWOC in patients with BPH/BPO who experience acute UR, TURP provides more favorable long-term clinical outcomes. The patients who received TURP had a lower risk of UTI, repeat UR episodes, and emergent bony fracture in the future than did those who received medication alone. We conclude that early surgical intervention should therefore be considered for such patients.