Gallstone disease is one of the most common digestive disorders. Acute gallstone disease causes severe pain and often requires emergency cholecystectomy when accompanied by acute cholecystitis.¹ Although gallstone disease itself is rarely fatal, treatment of gallstones is of substantial clinical importance, as emergency cholecystectomy has been associated with mortality rates ranging from 0.3% to 0.7%.^2,3 Furthermore, gallstone disease is the fourth most costly digestive disease in the United States, behind liver disease, gastroesophageal reflux disease, and colon cancer, accounting for a staggering annual expenditure of $6.2 billion.⁴ Consequently, effective management of gallstones can eliminate the need for cholecystectomy, which can reduce healthcare costs and lower mortality rates. The clinical implications are also significant because gallstone disease is associated with dyslipidemia, obesity, and cardiovascular disease, all of which are chronic metabolic diseases with a high prevalence and incidence.⁵

The prevalence of gallstone disease is increasing in Asia, and so are the associated healthcare costs. In particular, cholesterol and mixed gallstones are becoming increasingly more common as the prevalence of hypercholesterolemia increases because of the spread of Western dietary habits.^6,7 Accordingly, cholecystectomy rates are increasing every year in Asia, leading to significant increases in healthcare costs.^8,9 These trends highlight the urgent need for effective interventions and strategies to address gallstone disease, given its clinical impact and economic burden.¹⁰

Currently, cholecystectomy is recommended for the treatment of symptomatic gallstones, whereas oral litholysis is recommended for asymptomatic gallstone disease.^11,12 Oral litholysis therapy began in the 1970s with the introduction of chenodeoxycholic acid and ursodeoxycholic acid (UDCA). Since then, various drugs have been introduced, but UDCA is the only agent that is well-established and widely used at present.^13,14 The primary mechanism of action of UDCA is to reduce cholesterol saturation in the bile, thereby dissolving gallstones. Its response rate is approximately 50%.¹⁵ In addition to UDCA, ezetimibe, myriocin, capsaicin, and curcumin have been shown to effectively treat gallstones in animal studies, but their use has not yet been commercialized and requires further research.^16,17

Given the relatively low prevalence of cholesterol gallstone disease among Alaskan Natives and the increasing appearance of cholesterol gallstone complications among Canadian Inuit as their lifestyles shifted from a fish-based diet to a more Westernized diet,^18,19 we previously conducted animal experiments under the hypothesis that n-3 polyunsaturated fatty acids (PUFA) would be effective against cholesterol gallstones.²⁰ The results showed that PUFA protected against cholesterol gallstones in animals. PUFA attenuated gallstone formation in mice by increasing bile phospholipid levels and inhibiting bile mucin formation, and other animal studies confirmed that treatment with UDCA and PUFA reduced mucin production and cholesterol saturation and increased bile phospholipid and bile acid levels in mice, leading to the dissolution of cholesterol gallstones.²¹ Based on the results of these animal studies, we conducted a prospective randomized study in humans to compare gallstone dissolution rates between UDCA monotherapy (the only treatment currently available), and combination therapy with PUFA added to UDCA.

1. Study design and patients

This was a randomized, prospective, preliminary clinical trial. The protocol conformed to the ethical guidelines of the World Medical Association Declaration of Helsinki, was approved by the institutional review boards of all participating facilities (general approval no. 3-2018-0369), and was registered at cris.nih.go.kr (KCT0004722). Written informed consent was obtained from all patients, after which they were randomized according to a computer-generated randomization list into one of two groups: monotherapy group (UDCA alone) or combination group (UDCA plus PUFA). Opaque envelopes were used to conceal the randomization until assignment. All authors had access to the study data and reviewed and approved the final manuscript.

The patient inclusion criteria were as follows: age ≥19 years; gallbladder stones ≤15 mm in diameter detected on abdominal ultrasonography; no gallstones visible on plain abdominal X-ray; and no or only mild symptoms (pain <5 on a visual analog scale, occurring

2. Medication and follow-up

The monotherapy group was prescribed UDCA (URSA^Ⓡ; Daewoong Pharmaceutical Company, Seoul, Korea) 200 mg three times per day (at every meal), and the combination group was prescribed PUFA (Omacor^Ⓡ; Kuhnil Pharmaceutical Company, Seoul, Korea) 1,000 mg plus UDCA 200 mg three times per day (at every meal). Patients were monitored for drug use, complications, and laboratory tests every 3 months at Gangnam Severance Hospital, Yonsei University College of Medicine, Republic of Korea. Abdominal or endoscopic ultrasound was performed to evaluate the number and maximum diameter of gallstones before and at 6 months after initiating treatment. All participants were followed up from March 16, 2020, to October 25, 2021.

3. Primary efficacy endpoints

The primary endpoints were the gallstone dissolution rate and the response rate. The gallstone dissolution rate was defined as the percentage change in gallstone size from baseline to 6 months after beginning treatment, as measured by ultrasound. When distinct gallstone(s) were present, their size was measured using the ultrasound length measurement tool, and the maximum diameter of the largest stone was recorded as the gallstone size. When only gallbladder sludge was present, we could not measure the length and used the volume of sludge as the gallstone size instead. The volume was determined using this formula: 4/3π × r³(r=radius).

The treatment response rate was calculated as the proportion of patients showing any improvement post-administration of the treatment agent. We categorized treatment responses into three levels: complete, partial, or minimal. A complete response was defined as a 100% dissolution of gallstones, with none observed on post-treatment ultrasound examination. A partial response was defined as at least 50% dissolution of gallstones. Lastly, a minimal response was characterized by less than 50% dissolution of gallstones after treatment. The overall response rate to treatment was thus defined as the proportion of patients experiencing any level of response.

4. Secondary efficacy endpoint

The secondary endpoint was the incidence of clinical symptoms of gallstones. Clinical gallstone symptoms during treatment were defined as the occurrence of new-onset or worsening patient-reported abdominal discomfort or pain or the development of cholecystitis or cholangitis (diagnosed according to the Tokyo Guidelines 2018 criteria^22,23.

5. Adverse event assessment

The occurrence of adverse events was confirmed by personal interviews at 8-week intervals. The severity of adverse events was evaluated using the Common Terminology Criteria for Adverse Events grade, and the association of adverse events with the treatment was evaluated using the Naranjo algorithm.^24,25 If cholecystitis or cholangitis occurred, the study drugs were discontinued and appropriate treatment was provided, including referral to a surgeon for cholecystectomy or to an endoscopist for endoscopic retrograde cholangiopancreatography and stone removal.

6. Statistical analysis

All statistical analyses were performed using SAS (version 9.3, SAS Inc., Cary, NC, USA) and SPSS Statistics (version 18.0, IBM Corp., Armonk, NY, USA). Data are expressed as mean±standard deviation. Differences between monotherapy and combination groups for demographic variables, primary and secondary efficacy endpoints, and safety variables were evaluated using the independent two-sample t-test for continuous variables and the chi-square test (or Fisher exact test) for categorical variables. For continuous variables that did not exhibit normality, nonparametric methods were applied to perform the Mann-Whitney U test. To correct for differences between groups, we presented corrected p-values using the Quade test. Similarly, p-values for the overall response to treatment were corrected using logistic regression. A two-sided p-value of less than 0.05 was considered statistically significant.

1. Patient flowchart

During a screening of 59 potential study participants, five were excluded due to concomitant contraindications, two were excluded for a gallstone size >15 mm, and one withdrew consent. The remaining 51 patients were registered and randomly assigned to the monotherapy group (n=25) or combination group (n=26). In the monotherapy group, one patient dropped out because of consent withdrawal, and 24 patients completed the study. In the combination group, three patients dropped out because of consent withdrawal and two patients underwent cholecystectomy; the remaining 21 patients completed the study. Therefore, the final study population consisted of 45 patients (Fig. 1).

Figure 1. Flowchart of the study population. UDCA, ursodeoxycholic acid; PUFA, n-3 polyunsaturated fatty acids.

2. Baseline characteristics

There was no significant difference in age between groups (monotherapy vs combination: 51.7 years vs 52.6 years, p=0.844). Similarly, the sex distribution was not significantly different between groups (p=0.434). There were also no significant differences between groups with respect to height (monotherapy vs combination: 164.8 cm vs 165.5 cm, p=0.811) or weight (monotherapy vs combination: 68.6 kg vs 69.5 kg, p=0.827). Past medical history, complete blood count, and serum chemistry measurements were also similar between groups (Table 1).

Table 1 . Baseline Characteristics of the Study Participants.

Variable	UDCA group (n=24)	UDCA + PUFA group (n=21)	Reference range	p-value
Basic characteristics
Age, yr	51.7±18.8	52.6±11.6		0.844
Sex (M:F)	12:12	8:13		0.434
Height, cm	164.8±9.6	165.5±9.6		0.811
Weight, kg	68.6±13.4	69.5±14.3		0.827
Past medical history
Hypertension	4 (16.7)	4 (19.0)
Diabetes mellitus	2 (8.3)	1 (4.8)
Menopausal or postmenopausal	3 (12.5)	4 (19.0)
Complete blood count
WBC, ×103/μL	6.3±1.6	6.4±1.9	4.0–10.8	0.860
RBC, ×106/μL	4.6±0.6	4.7±0.5	4.0–5.4	0.762
Hemoglobin, g/dL	14.0±1.6	14.3±1.3	11–17	0.553
Platelets, ×103/μL	260.1±54.2	226.5±56.2	150–400	0.148
Serum chemistry
BUN, mg/dL	14.0±3.7	13.4±2.9	8.6–23.0	0.560
Creatinine, mg/dL	0.8±0.1	0.7±0.1	0.72–1.18	0.970
γ-GTP, IU/L	37.2±53.7	58.7±55.6	8–46	0.195
ALP, IU/L	81.9±45.0	79.1±23.4	39–111	0.801
SGOT, IU/L	22.6±8.9	26.2±18.8	16–37	0.209
SGPT, IU/L	23.5±24.1	26.9±18.8	11–46	0.609
Total bilirubin mg/dL	0.9±0.5	0.7±0.3	0.3–1.8	0.116
Cholesterol, mg/dL	253.2±314.3	198.4±40.9	<200	0.433
HDL-cholesterol, mg/dL	48.1±10.8	51.6±11.7	40–60	0.302
LDL-cholesterol, mg/dL	109.6±22.6	116.4±28.7	<100	0.376
Triglycerides, mg/dL	120.8 ± 62.5	152.3±127.0	<150	0.288

Data are presented as mean±SD or number (%)..

UDCA, ursodeoxycholic acid; PUFA, n-3 polyunsaturated fatty acids; M, male; F, female; WBC, white blood cells; RBC, red blood cells; BUN, blood urea nitrogen; γ-GTP, gamma-glutamyl transferase; ALP, alkaline phosphatase; SGOT, serum glutamic-oxaloacetic transaminase; SGPT, serum glutamic-pyruvic transaminase; HDL, high-density lipoprotein; LDL, low-density lipoprotein..

3. Efficacy outcomes

Dissolution of gallstones was assessed by pre- and post-treatment ultrasound (Fig. 2). Before treatment, distinct gallbladder stones were observed in 19 patients (79.2%) in the monotherapy group and 11 patients (52.4%) in the combination group. In the monotherapy group, the mean gallstone size was 8.9 mm before treatment and 9.1 mm after treatment, the median number of gallstones was two before treatment and one after treatment, with a mean stone dissolution rate of –6.2%. In the combination group, the mean gallstone size was 9.0 mm before treatment and 8.2 mm after treatment, the median number of gallstones was four before treatment and two after treatment, with a mean stone dissolution rate of 9.3%. Regarding gallstone response rates, complete response was observed in 5.3% of the monotherapy group and 9.1% of the combination therapy group. Partial response rates were 0.0% in both groups. Although these rates did not differ significantly between the groups, there was a notable difference in minimal response rates (26.3% in the monotherapy group vs 72.7% in the combination group, p=0.023) and overall response rates (31.6% in the monotherapy group vs 81.8% in the combination group, p=0.021). While gallbladder stone dissolution rates did not differ significantly between the groups (p=0.361), significant differences were observed in the change in the number of gallstones (p=0.049) and in overall response rate (p=0.021) (Table 2).

Figure 2. Abdominal ultrasound findings before and after combination therapy. (A) Before treatment, multiple gallstones were identified within the gallbladder. (B) By 6 months after treatment, all gallstones previously seen in A had disappeared. (C) Before treatment, a large amount of gallbladder sludge was identified within the gallbladder. (D) By 6 months after treatment, most of the gallbladder sludge previously seen in C had disappeared.

Table 2 . Gallstone Dissolution Rates and Response to Treatment.

Variable	UDCA group (n=24)	UDCA + PUFA group (n=21)	p-value	Adjusted p-value
Distinct gallbladder stones
Number of patients	19 (79.2)	11 (52.4)	0.057
Pre-treatment, mm	8.9±3.1	9.0±2.9	0.950
Post-treatment, mm	9.1±4.5	8.2±4.4	0.593
Dissolution rate, %	–6.2±40.1	9.3±50.7	0.361
Pre-treatment, number of stones	2.0 (1.0 to 4.0)	4.0 (1.0 to 10.0)	0.352
Post-treatment, number of stones	1.0 (1.0 to 2.0)	2.0 (1.0 to 4.0)	0.803
Difference in the number of stones	0.0 (–1.0 to 0.0)	2.0 (–4.0 to 0.0)	0.049
Complete response rate	1 (5.3)	1 (9.1)	1.000
Partial response rate	0	0	1.000
Minimal response rate	5 (26.3)	8 (72.7)	0.023
Overall response to treatment	6 (31.6)	9 (81.8)	0.021
Gallbladder sludge only
Number of patients	5 (20.8)	10 (47.6)	0.057
Pre-treatment, mm3	11,060±14,306	39,528±99,256	0.668
Post-treatment, mm3	623±667	1,301± 2,016	0.800
Dissolution rate, %	71.4±42.9	85.8±18.8	0.527
Complete response rate	2 (40.0)	5 (50.0)	1.000
Partial response rate	2 (40.0)	4 (40.0)	1.000
Minimal response rate	0	1 (10.0)	1.000
Overall response to treatment	4 (80.0)	10 (100.0)	0.333
Gallbladder stones and sludge
Overall dissolution rate, %	9.9±51.1	45.7±54.6	0.009	0.070
Complete response rate	3 (12.5)	6 (28.6)	0.267	0.595
Partial response rate	2 (8.3)	4 (19.0)	0.396	0.993
Minimal response rate	5 (20.8)	9 (42.9)	0.111	0.014
Overall response to treatment	10 (41.7)	19 (90.5)	<0.001	0.007

Data are presented as number (%), mean±SD, or median (interquartile range)..

UDCA, ursodeoxycholic acid; PUFA, n-3 polyunsaturated fatty acids..

Before treatment, only gallbladder sludge was present in five patients in the monotherapy group and 10 patients in the combination group. In the monotherapy group, the mean sludge volume was 11,060 mm³ before treatment and 623 mm³ after treatment, with a mean sludge dissolution rate of 71.4% and an overall response rate of 80.0%. In the combination group, the mean sludge volume was 39,528 mm³ before treatment and 1,301 mm³ after treatment, with a mean sludge dissolution rate of 85.8% and an overall response rate of 100.0%. These gallbladder sludge dissolution rates and overall response rates were not significantly different between groups (p=0.527 and p=0.333) (Table 2).

When considering all patients (with stones or sludge), the overall gallstone dissolution rate tended to be higher in the combination therapy group than in the monotherapy group (45.7% vs 9.9%, p=0.070) (Fig. 3). Furthermore, the rates of overall response (90.5% vs 41.7%, p=0.007) and minimal response (42.9% vs 20.8%, p=0.014) were significantly higher in the combination therapy group compared to the monotherapy group (Table 2).

Figure 3. Gallstone dissolution rates and response to treatment. (A) In the UDCA monotherapy group, 10 patients responded to gallstone dissolution treatment (41.7% response rate), and the overall dissolution rate was 9.9%. (B) In the UDCA plus PUFA combination therapy group, 19 patients responded to gallstone dissolution treatment (90.5% response rate), and the overall dissolution rate was 45.7%. The overall gallstone dissolution rate was significantly higher in the combination therapy group than in the monotherapy group (p=0.028). UDCA, ursodeoxycholic acid; PUFA, n-3 polyunsaturated fatty acids.

Regarding clinical symptoms of gallstones, cholecystectomy for onset or worsening of right upper quadrant pain was reported in two (9.5%) patients in the combination group and no patients in the monotherapy group. The difference in incidence of symptoms between groups was not statistically significant (p=0.126). No patient in either group was diagnosed with cholecystitis or cholangitis during treatment.

4. Adverse events

Adverse events were compared between the monotherapy group (n=24) and combination group (n=21). A total of four adverse events were reported, two in each group (p=0.890) (Table 3). The adverse events were esophageal pain, dyspepsia, back pain, and vaginal infection, with no other symptoms or abnormalities in liver function tests. No association between UDCA or PUFA and adverse events was observed according to the Naranjo algorithm. None of these events were related to gallstones, all were Common Terminology Criteria for Adverse Events grade 2, and all resolved with conservative treatment.

Table 3 . Adverse Events during Gallstone Treatment.

Variable	Grade*	UDCA group (n=24)	UDCA+PUFA group (n=21)	p-value
Gastrointestinal disorders, No. (%)
Esophageal pain	2	0	1 (4.8)	0.285
Dyspepsia	2	1 (4.2)	0	0.350
Musculoskeletal and connective tissue disorders, No. (%)
Back pain	2	1 (4.2)	0	0.350
Infections and infestations, No. (%)
Vaginal infection	2	0	1 (4.8)	0.285
Total adverse events rate	-	2 (8.3)	2 (9.5)	0.890

UDCA, ursodeoxycholic acid; PUFA, n-3 polyunsaturated fatty acids..

*Common Terminology Criteria for Adverse Events grade..

In this preliminary clinical trial, we evaluated the efficacy and safety of combination therapy with UDCA and PUFA versus UDCA monotherapy in patients with cholesterol gallstones. Our results showed that UDCA plus PUFA combination therapy dissolves cholesterol gallstones more effectively than UDCA monotherapy, which aligns with the results of previous animal studies showing protective effects of PUFA against cholesterol gallstones.^20,21 We found that the gallstone treatment response rate was significantly higher in the patients receiving combination therapy than in those receiving UDCA alone. In addition, the gallstone dissolution rates tended to be higher in the combination group, compared to the monotherapy group. It is also important to note that with both types of treatment, the dissolution and response rates were higher in patients with gallbladder sludge than in those with distinct gallbladder stones. These findings suggest that combination therapy might be particularly beneficial for patients with sludge-type gallstones, although further investigation is required to confirm this.

The superior efficacy of combination therapy for gallstone dissolution can be attributed to the distinct but complementary mechanisms of UDCA and PUFA. UDCA promotes the dissolution of cholesterol gallstones primarily by increasing bile acid concentrations,^13,14 whereas PUFA dissolves cholesterol gallstones by increasing phospholipid levels in bile, thereby reducing cholesterol saturation and interfering with bile mucin formation.²⁰ In addition, the combination of PUFA and UDCA appears to suppress the expression of genes responsible for mucin biosynthesis.²¹ This downregulation affects gallbladder secretion of mucin, an important component in gallstone formation, thereby further contributing to the superior performance of combination therapy versus UDCA monotherapy in the treatment of gallstones. Thus, combination therapy with this multi-targeted approach provides a comprehensive strategy for more effective gallstone dissolution.

There are two important issues to consider regarding our results. The first is that although statistical differences were seen in overall dissolution rates and response rates between monotherapy and combination therapy, they were not statistically significant when gallbladder stones and gallbladder sludge were considered separately.

In this study, subgroup analysis revealed differences that may be attributed to the relatively small sample size and the uneven distribution of gallstones and sludge between the monotherapy and combination therapy groups. To address this, we initially assessed the normality of our data using the Shapiro-Wilk test. For variables that did not exhibit normal distribution, we employed nonparametric tests, such as the Mann-Whitney U test or the Kruskal-Wallis test (Supplementary Table 1). Furthermore, to statistically account for the imbalance in the distribution of gallstones and sludge, we performed an analysis using the Quade test to adjust for covariates in our assessment of the overall dissolution rate. Additionally, we applied logistic regression analysis to adjust for confounders, thereby refining our calculation of the overall response rate and presenting these findings with adjusted p-values. The second issue is that both monotherapy and combination therapy were more effective against gallbladder sludge than against distinct gallbladder stones. This finding may be related to the duration of the study and the nature of the gallstones. Most studies analyzing the effectiveness of UDCA for gallstone dissolution have followed gallstones for >12 months.²⁶ These studies found that gallstones became increasingly difficult to dissolve as their diameter increased. Therefore, our 6-month study period is relatively short, and while this time may have been adequate for dissolving smaller gallstones (e.g., sludge), it may not be sufficient for larger stones. Indeed, previous studies reported that while symptoms resolved after 3 months of UDCA administration, complete dissolution of gallstones required an average of 12 months.^27,28

In addition, the nature of the gallstones may affect UDCA effectiveness. One prospective study found that the dissolution rate during 12 months of UDCA therapy varied according to gallstone density measured by computed tomography.²⁹ Similarly, a retrospective analysis found that treatment failure after 9 months of UDCA treatment occurred mostly in patients with non-cholesterol stones.³⁰ These observations emphasize the need for gallstone screening and suggest that UDCA therapy should be used conditionally in cholesterol gallstones, depending on the type and size of the stone. However, in clinical practice, computed tomography for the diagnosis of cholesterol gallstones is undesirable due to cost and radiation exposure. Considering these factors, this study included patients with gallstones that were not visible on plain abdominal X-ray but were diagnosed by showing a posterior acoustic shadow on ultrasound, which is limited in diagnosing the exact nature of the gallstones.³¹ Therefore, we cannot exclude the possibility that differences in dissolution rates were due to differences in gallstone composition. However, our use of ultrasound alone for diagnosing gallstones has “real-world” applicability, as this is the diagnostic modality most likely to be used clinically.

Since this study was conducted in humans, safety is the most important issue. The safety of UDCA has been confirmed in many studies, as well as in clinical practice.^32,33 In this study, we used UDCA 600 mg/day, which is the optimal UDCA dose proven to be safe.^34,35 PUFA has also been studied extensively, and its safety has also been established, with a wide range of dosages recommended for different purposes. For example, the American Heart Association recommends doses of 1,000–4,000 mg/day for preventing heart disease,^36-38 whereas doses of 200–2,200 mg/day have been used for treating depression and anxiety.^39-41 As such, doses up to 4,000 mg have been demonstrated to be safe in humans, and 3,000 mg (the dose used in this study) has been used safely by previous investigators.^42,43 In addition, PUFA is the fifth most commonly used dietary supplement in Korea, with sales of $78,371,866 in 2019,^44,45 and UDCA is frequently prescribed for patients with hepatobiliary disease. Despite their widespread usage, there have been no reports of drug interactions between UDCA and PUFA. Consequently, although no previously published human studies used the combination of UDCA 600 mg and PUFA 3,000 mg, we hypothesized that this combination would be safe. Our results confirmed this hypothesis.

Although efficacy was increased with combination therapy, there were no drug-related adverse events in either the combination or monotherapy groups. None of the adverse events observed during the study were considered drug-related, and none led to drug discontinuation. Thus, the favorable safety profile supports the use of UDCA plus PUFA combination therapy as a viable therapeutic option for patients with cholesterol gallstones. Furthermore, in this prospective randomized controlled trial, two patients in the combination therapy arm were diagnosed with acute cholecystitis and were removed from the study. In the first case, a patient diagnosed with cholelithiasis had a gallstone measuring 1.4 cm. Four months after starting combination therapy, the patient presented to the emergency department with abdominal pain and was diagnosed with acute cholecystitis. Subsequent cholecystectomy revealed that the gallstone size had decreased to 0.7 cm, a 50.0% reduction. The second case involved a patient whose gallstones were found to be 1.2 cm in size at the time of diagnosis of cholelithiasis. Although surgical intervention was recommended for symptomatic gallstone, the patient opted for drug therapy and enrolled in the study. After 2 months of combination therapy, the patient experienced abdominal pain, was diagnosed with acute cholecystitis, and underwent cholecystectomy. Postoperative examinations showed that the size of the gallstones remained unchanged at 1.2 cm. It is noteworthy that 20% to 80% of patients with gallstone are asymptomatic, and the transition from asymptomatic to symptomatic status varies with a reported range of 11.7% to 23.7%.^46,47 In addition, the incidence of symptomatic recurrence in patients with asymptomatic gallstone is quite high, ranging from 18.6% to 37.1%.⁴⁸ The incidence of cholecystectomy due to symptomatic development during drug therapy in this study is within previously reported rates and is an expected outcome. Furthermore, the analysis showed no significant difference in the proportion of patients requiring cholecystectomy between the monotherapy and combination therapy groups. These results demonstrate that combination therapy does not increase the risk of requiring cholecystectomy due to acute cholecystitis. Nevertheless, careful monitoring for the possible development of acute cholecystitis is essential during drug treatment of asymptomatic gallstone patients.

Nevertheless, it is essential to realize that our study is a preliminary clinical trial, with a relatively small sample size. Therefore, larger-scale, multicenter studies are required to confirm our findings and further investigate the therapeutic effects of UDCA plus PUFA combination therapy in patients with cholesterol gallstones. Despite this limitation, our study contributes to the understanding of the therapeutic potential of PUFA in the management of cholesterol gallstones and opens a new avenue for improving gallstone treatment.

In summary, our findings suggest that compared to UDCA monotherapy, the combination of UDCA plus PUFA can be a superior therapeutic approach for cholesterol gallstones, given its higher dissolution and response rates and lack of significant complications. Future prospective, large-scale clinical trials are warranted to confirm our findings and better understand the therapeutic potential of UDCA plus PUFA combination therapy for cholesterol gallstones.

This study was funded by the National Research Foundation, Ministry of Science, and ICT of Korea (NRF-2017R1A2B2011840 and 2020R1A2C1100753), a grant of Patient-Centered Clinical Research Coordinating Center (PACEN) funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HC21C0016), and a faculty research grant from the Yonsei University College of Medicine (6-2012-0113 and 6-2023-0209).

No potential conflict of interest relevant to this article was reported.

Study concept and design: S.I.J., D.K.L. Data analysis and interpretation: S.Y.L. (1st author), S.I.J., J.H.C., M.Y.D., S.Y.L. (5th author), A.C., H.S.L., J.Y., D.K.L. Drafting of the manuscript: S.Y.L. (1st), S.I.J., D.K.L. Critical revision of the manuscript for important intellectual content: J.H.C., M.Y.D., H.S.L., J.Y. Obtained funding: S.I.J., J.H.C., D.K.L. Administrative, technical, or material support; study supervision: S.I.J., S.Y.L. (5th), A.C., D.K.L. Approval of final manuscript: all authors.

Supplementary materials can be accessed at https://doi.org/10.5009/gnl230494.