Abstract
We systematically searched available databases. We reviewed 6,143 studies published from 1833 to 2017. Reports in English, French, German, Italian, and Spanish were considered, as were publications in other languages if definitive treatment and recurrence at specific follow-up times were described in an English abstract. We assessed data in the manner of a meta-analysis of RCTs; further we assessed non-RCTs in the manner of a merged data analysis. In the RCT analysis including 11,730 patients, Limberg & Dufourmentel operations were associated with low recurrence of 0.6% (95%CI 0.3–0.9%) 12 months and 1.8% (95%CI 1.1–2.4%) respectively 24 months postoperatively. Analysing 89,583 patients from RCTs and non-RCTs, the Karydakis & Bascom approaches were associated with recurrence of only 0.2% (95%CI 0.1–0.3%) 12 months and 0.6% (95%CI 0.5–0.8%) 24 months postoperatively. Primary midline closure exhibited long-term recurrence up to 67.9% (95%CI 53.3–82.4%) 240 months post-surgery. For most procedures, only a few RCTs without long term follow up data exist, but substitute data from numerous non-RCTs are available. Recurrence in PSD is highly dependent on surgical procedure and by follow-up time; both must be considered when drawing conclusions regarding the efficacy of a procedure.
Introduction
For unknown reasons, the incidence of pilonidal sinus disease (PSD) has risen continuously during the past 50 years, particularly in European and North American young men1,2. In a German military cohort for example, the number of affected patients increased from 29/100,000 in 2000 to 48/100,000 in 2012, and the total number of PSD-related in-patient surgeries exceeded the number of inguinal hernia-related interventions in 20 to 40-year-old patients3. Recurrent disease may probably affect patients’ long-term satisfaction following PSD surgery4. Recurrence between 0 percent5 and 100 percent6 has been reported for PSD, and wide recurrence range can be seen even within the different surgical approach techniques as open treatment, primary midline closure or flap techniques and others. Some evidence suggests that recurrence is associated with surgical procedure and correlated with length of follow-up as well4,7. However, the data are conflicting, and applied follow-up times often appear to have been randomly chosen, which brings into question the validity of reported recurrence associated with different surgical procedures. The purpose of this meta-analysis and merged data analysis was therefore to obtain a comprehensive assessment of recurrence and to ascertain determinants of recurrence of PSD with respect to specific surgical procedures and follow-up time. We considered both randomised controlled trials (RCTs) and non-RCTs.
We thus assembled a database with sources from the first description of PSD in 1833 on, that included reported recurrence, year of publication, timeframes of follow-up, type of study, and patient- and procedure-specific factors. We grouped therapeutic procedures for cumulative statistical analyses (Table 1). Using this dataset, we assessed the efficacy of common surgical procedures employed in treating PSD as a function of recurrence. We found that the recurrence in PSD varied depending on the surgical procedure and on the length of follow-up. While naturally, an increase of recurrence could be observed with longer follow-up, the rate of this increase was varying among the different procedures. This indicates that a thorough evaluation of a procedure in view of recurrence has to include the specific relation of recurrence to follow-up time and cannot just be based on comparisons at one single follow-up time. The strength of our conclusions is substantially buttressed by the extensive analysis of a large database pertaining to particular therapeutic procedures.
Results
Our search criteria retrieved 5,840 studies and 303 book chapters across all databases. After excluding duplicates, 5,768 studies were screened. Reports on PSD in other than the classical presacral intergluteal location, studies in embryonic development, in carcinomas, etc. were excluded. Following exclusion, 1,148 articles on PSD at classical anatomical location with specific surgical treatment remained for analysis. Of these, 408 lacked detailed data on recurrence or follow-up time or both. Finally, 740 studies published from 1833 to 2017 were analysed. A flow chart describing the selection of literature sources, based on the Preferred reporting items for systematic reviews and meta-analysis (PRISMA)8, is illustrated in Fig. 1.
Flow diagram based on Preferred reporting items for systematic reviews and meta-analysis (PRISMA)8 illustrating the systematic search for evidence regarding recurrence and long term follow-up data associated with common surgical procedures in PSD.
Results reported in the final set of publications were stratified according to the specific surgical technique employed to avoid bias across studies. This approach led to 14 groups for analysis. Additionally, we included an overall analysis. For each of the specific therapeutic approaches, the data included the number of patients, the reported follow-up time, and the recurrence.
Heterogeneity analysis
Considering prospective/randomized control trials only, the heterogeneity analysis showed I2 < 5%, p > 0.2 (Cochrane’s Q-test) except for the Bascom/Karydakis (0–12 months, p < 0.001, I2 = 80.36%, df = 4), marsupialisation (0–12 months; p < 0.001, I2 = 97.84%, df = 3), and other flap techniques (0–12 months, p = 0.062, I2 = 64%, df = 2). Considering all studies, the heterogeneity analysis showed I2 < 5%, p > 0.2 (Cochrane’s Q-test) except for the primary asymmetric closure (0–12 months, p = 0.023, I2 = 61.54%, df = 5), marsupialisation (0–12 months, p < 0.001, I2 = 64.43%, df = 18), and pit picking (0–12 months, p < 0.001, I2 = 98.31%, df = 6).
The above described analysis ascertains that there is no statistical evidence of heterogeneity in our study group, except for primary asymmetric closure, marsupialisation and pit picking.
Follow-up time and recurrence over all surgical therapies
Data on recurrence and follow-up times in all surgical PSD treatments together pertaining to 11,700 patients were extracted from 102 RCTs2,5,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110. A recurrence of 1.5% (95% CI 1.3–1.8%) was observed in patients at 12 months, 4.3% (95% CI 3.8–4.8%) at 24 months, and 20.3% (95% CI 17.8–22.9%) at 60 months.
Further, data on recurrence and follow-up times in all surgical PSD treatments together pertaining to primary open PSD treatment pertaining to a total of 89,583 patients were extracted from 638 additional non-RCTs4,62,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,256,257,258,259,260,261,262,263,264,265,266,267,268,269,270,271,272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288,289,290,291,292,293,294,295,296,297,298,299,300,301,302,303,304,305,306,307,308,309,310,311,312,313,314,315,316,317,318,319,320,321,322,323,324,325,326,327,328,329,330,331,332,333,334,335,336,337,338,339,340,341,342,343,344,345,346,347,348,349,350,351,352,353,354,355,356,357,358,359,360,361,362,363,364,365,366,367,368,369,370,371,372,373,374,375,376,377,378,379,380,381,382,383,384,385,386,387,388,389,390,391,392,393,394,395,396,397,398,399,400,401,402,403,404,405,406,407,408,409,410,411,412,413,414,415,416,417,418,419,420,421,422,423,424,425,426,427,428,429,430,431,432,433,434,435,436,437,438,439,440,441,442,443,444,445,446,447,448,449,450,451,452,453,454,455,456,457,458,459,460,461,462,463,464,465,466,467,468,469,470,471,472,473,474,475,476,477,478,479,480,481,482,483,484,485,486,487,488,489,490,491,492,493,494,495,496,497,498,499,500,501,502,503,504,505,506,507,508,509,510,511,512,513,514,515,516,517,518,519,520,521,522,523,524,525,526,527,528,529,530,531,532,533,534,535,536,537,538,539,540,541,542,543,544,545,546,547,548,549,550,551,552,553,554,555,556,557,558,559,560,561,562,563,564,565,566,567,568,569,570,571,572,573,574,575,576,577,578,579,580,581,582,583,584,585,586,587,588,589,590,591,592,593,594,595,596,597,598,599,600,601,602,603,604,605,606,607,608,609,610,611,612,613,614,615,616,617,618,619,620,621,622,623,624,625,626,627,628,629,630,631,632,633,634,635,636,637,638,639,640,641,642,643,644,645,646,647,648,649,650,651,652,653,654,655,656,657,658,659,660,661,662,663,664,665,666,667,668,669,670,671,672,673,674,675,676,677,678,679,680,681,682,683,684,685,686,687,688,689,690,691,692,693,694,695,696,697,698,699,700,701,702,703,704,705,706,707,708,709,710,711,712,713,714,715,716,717,718,719,720,721,722,723,724,725,726,727,728,729,730,731,732,733,734,735,736,737,738,739,740,741,742,743,744,745,746. Among these patients, a recurrence of 2.0% (95% CI 1.9–2.1%) was observed in patients at 12 months, 4.4% (95% CI 4.3–4.6%) at 24 months, 10.8% (95% CI 10.5–11.3%) at 60 months, 16.9% (95% CI 16.3–17.5%) at 120 months, and 60.4% (95% CI 47.1–37.8%) at 240 months (Fig. 4).
Procedure specific recurrence rates in PSD [%]* derived from RCTs. *Data of homogeneous recurrence rates (I2 < 5%, p > 0.2) are printed in bold, heterogeneous data in italic numbers; **includes Bascom cleft lift; ***includes Bascom Pit Picking.
Procedure specific recurrence rates in PSD [%]* overall derived from RCTs and non-RCTs. *Data of homogeneous recurrence rates (I2 < 5%, p > 0.2) are printed in bold, heterogeneous data in italic numbers; **includes Bascom cleft lift, ***includes Bascom Pit Picking.
Recurrence free outcome as a function of follow-up time irrespective of specific therapeutic procedure. Data presented are for RCTs only and for all available studies. Numbers of patients included in the analysis are indicated at 12, 24, 60, and 120 months. Dashed lines indicate 95% confidence intervals.
To enable an entire picture, this overall analysis included data on recurrence and follow-up times pertaining to 184 patients treated for PSD by other methods (Table 1) extracted from 3 RCTs. Among these patients, a recurrence of 3.8% (95% CI 0.9–6.7%) was observed in patients at 12 months and 7.8% (95% CI 0.4–15.1%) at 24 months and follow-up times pertaining to 2,916 patients treated for PSD by other methods extracted from 40 additional non-RCTs. Among these patients, a recurrence of 2.9% (95% CI 2.2–3.7%) was observed in patients at 12 months, 6.7% (95% CI 5.4–8.0%) at 24 months, and 26.0% (95% CI 22.6–29.4%) at 60 months.
To provide a rational basis for selecting treatment approaches, we assessed possible associations between recurrence of PSD and specific therapeutic procedures in the manner of a classical meta-analysis of RCTs, and found that recurrence in common surgical procedures for PSD were dependent on follow-up time (Figure 2); additional data from non-RCTs were included and processed in the manner of a merged data analysis (Figure 3).
Recurrence in primary open PSD treatment
Data on recurrence and follow-up times in primary open PSD treatment pertaining to 1,713 patients were extracted from 32 RCTs9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,747,748. Among these patients, a recurrence of 1.0% (95% CI 0.5–1.6%) was observed in patients at 12 months, 3.2% (95% CI 2.2–4.2%) at 24 months, and 16.5% (95% CI 11.9–21.2%) at 60 months.
Further, data on recurrence and follow-up times in primary open PSD treatment pertaining to 10,166 patients were extracted from 128 additional non-RCTs4,39,40,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234. Among these patients, a recurrence of 1.5% (95% CI 1.2–1.7%) was observed in patients at 12 months, 4.2% (95% CI 3.7–4.7%) at 24 months, 13.1% (95% CI 11.9–14.4%) at 60 months, and 19.9% (95% CI 17.9–21.9%) at 120 months (Fig. 5).
Recurrence free outcome as a function of follow-up time of patients receiving primary open treatment. Data presented are for RCTs only and for all available studies. Numbers of patients included in the analysis are indicated at 12, 24, 60, and 120 months. Dashed lines indicate 95% confidence intervals.
Recurrence in primary midline closures
Data on recurrence and follow-up times in primary midline closures (not using advancement or rotation flap techniques) pertaining to 4,626 PSD patients which were extracted from 51 RCTs5,9,10,19,20,22,25,26,27,28,29,31,32,35,37,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,235,236,748. Among these patients, a recurrence of 2.1% (95% CI 1.7–2.6%) was observed in patients at 12 months, 7.0% (95% CI 6.0–8.0%) at 24 months, and 21.9% (95% CI 18.5–25.3%) at 60 months.
Data on recurrence and follow-up times in primary open PSD treatment pertaining to 21,583 patients were extracted from 205 additional non-RCTs4,60,74,75,111,112,114,115,117,118,121,122,123,124,125,126,128,129,130,131,132,133,134,136,137,141,143,149,153,154,155,156,160,161,163,167,168,169,170,171,174,175,177,181,182,188,189,190,191,192,194,196,197,199,200,201,203,206,208,215,216,218,220,221,223,224,230,233,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,256,257,258,259,260,261,262,263,264,265,266,267,268,269,270,271,272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288,289,290,291,292,293,294,295,296,297,298,299,300,301,302,303,304,305,306,307,308,309,310,311,312,313,314,315,316,317,318,319,320,321,322,323,324,325,326,327,328,329,330,331,332,333,334,335,336,337,338,339,340,341,342,343,344,345,346,347,348,349,350,351,352,353,354,355,356,357,358,359,360,361,362,363,364,365,366,367,368,369,370,371,372,373. Among these patients, a recurrence of 3.4% (95% CI 3.1–3.6%) was observed in patients at 12 months, 7.0% (95% CI 6.5–7.4%) at 24 months, 16.8% (95% CI 15.8–17.8%) at 60 months, 32.0% (95% CI 29.6–34.4%) at 120 months, and 67.9% (95% CI 53.3–82.4%) at 240 months (Fig. 6).
Recurrence free outcome as a function of follow-up time of patients treated with primary midline closure (not using advancement or rotation flap techniques). Data presented are for RCTs only and for all available studies. Numbers of patients included in the analysis are indicated at 12, 24, 60, and 120 months. Dashed lines indicate 95% confidence intervals.
Recurrence in primary asymmetric closure
Data on recurrence and follow-up times in primary asymmetric closure PSD treatment pertaining to 119 patients were extracted from 2 RCTs34,374. Among these patients, a recurrence of 7.3% (95% CI 0.0–19.9%) was observed in patients at 12 months.
Further, data on recurrence and follow-up times pertaining to 3,121 patients receiving primary open PSD treatment were extracted from 28 additional non-RCTs4,76,130,133,139,157,221,228,320,348,357,375,376,377,378,379,380,381,382,383,384,385,386,387,388,389,390,391. Among these patients, a recurrence of 1.0% (95% CI 0.6–1.4%) was observed in patients at 12 months, 1.6% (95% CI 1.1–2.1%) at 24 months, 3.2% (95% CI 2.3–4.0%) at 60 months, and 6.7% (95% CI 5.2–8.2%) at 120 months (Fig. 7).
Recurrence free outcome as a function of follow-up time of patients treated with primary asymmetric closure. Data presented are for RCTs only and for all available studies. Numbers of patients included in the analysis are indicated at 12, 24, 60, and 120 months. Dashed lines indicate 95% confidence intervals.
Recurrence in Karydakis and Bascom cleft lift techniques
Data on recurrence and follow-up times pertaining to 1,457 patients treated for PSD by a Karydakis or Bascom cleft lift technique were extracted from 21 RCTs24,33,59,62,63,77,78,79,80,81,82,83,84,85,86,87,88,89,90,392,393. Among these patients, a recurrence of 1.5% (95% CI 0.8–2.2%) was observed in patients at 12 months, 2.4% (95% CI 1.4–3.3%) at 24 months, and 10.2% (95% CI 5.4–15.0%) at 60 months.
Data on recurrence and follow-up times pertaining to 16,349 patients treated for PSD by a Karydakis and Bascom cleft lift technique were extracted from 66 additional non-RCTs91,92,136,146,161,163,184,198,206,254,263,313,335,346,348,361,379,391,394,395,396,397,398,399,400,401,402,403,404,405,406,407,408,409,410,411,412,413,414,415,416,417,418,419,420,421,422,423,424,425,426,427,428,429,430,431,432,433,434,435,436,437,438,439,440,441. Among these patients, a recurrence of 0.2% (95% CI 0.1–0.3%) was observed in patients at 12 months, 0.6% (95% CI 0.5–0.8%) at 24 months, 1.9% (95% CI 1.6–2.2%) at 60 months, and 2.7% (95% CI 2.4–3.1%) at 120 months (Fig. 8). Along with the Limberg/Dufourmentel approaches and other flap techniques, the Karydakis and Bascom cleft lift procedures resulted in the lowest recurrence at any follow-up time in our analysis (Tables 2 and 3).
Recurrence free outcome as a function of follow-up time of patients treated with Bascom and Karydakis techniques. Data presented are for RCTs only and for all available studies. Numbers of patients included in the analysis are indicated at 12, 24, 60, and 120 months. Dashed lines indicate 95% confidence intervals.
Recurrence in Limberg and Dufourmentel flaps
Data on recurrence and follow-up times pertaining to 2,380 patients treated for PSD by Limberg and Dufourmentel flap techniques were extracted from 36 RCTs5,14,21,23,43,44,46,49,53,54,56,61,64,65,73,77,78,80,82,83,90,93,94,95,96,97,98,99,100,101,102,236,392,393,442,443. Among these patients, a recurrence of 0.6% (95% CI 0.3–0.9%) was observed in patients at 12 months and 1.8% (95% CI 1.1–2.4%) at 24 months.
Data on recurrence and follow-up times pertaining to 12,384 patients treated for PSD by Limberg and Dufourmentel flaps were extracted from 139 additional non-RCTs4,60,103,104,115,126,127,128,133,156,157,196,199,201,208,221,224,242,261,262,267,289,302,303,313,318,321,322,334,335,336,348,372,399,407,410,415,417,426,433,438,439,444,445,446,447,448,449,450,451,452,453,454,455,456,457,458,459,460,461,462,463,464,465,466,467,468,469,470,471,472,473,474,475,476,477,478,479,480,481,482,483,484,485,486,487,488,489,490,491,492,493,494,495,496,497,498,499,500,501,502,503,504,505,506,507,508,509,510,511,512,513,514,515,516,517,518,519,520,521,522,523,524,525,526,527,528,529,530,531,532,533,534,535,536,537,538,539,540,541. Among these patients, a recurrence of 0.4% (95% CI 0.3–0.5%) was observed in patients at 12 months, 1.6% (95% CI 1.3–1.9%) at 24 months, 5.2% (95% CI 4.5–5.8%) at 60 months, and 11.4% (95% CI 9.2–13.7%) at 120 months (Fig. 9).
Recurrence free outcome as a function of follow-up time of patients treated with Limberg and Dufourmentel flap technique. Data presented are for RCTs only and for all available studies. Numbers of patients included in the analysis are indicated at 12, 24, 60, and 120 months. Dashed lines indicate 95% confidence intervals.
Recurrence in other flap techniques
Data on recurrence and follow-up times pertaining to 283 patients treated for PSD by other flap techniques were extracted from 6 RCTs45,55,98,105,542,543. Among these patients, a recurrence of 0.4% (95% CI 0.0–1.1%) was observed in patients at 12 months and 7.5% (95% CI 2.4–12.5%) at 24 months.
Data on recurrence and follow-up times pertaining to 4,258 patients treated for PSD by other flap techniques were extracted from 89 additional non-RCTs106,107,111,126,137,160,167,182,192,208,221,224,233,245,259,283,312,321,339,354,368,410,433,449,492,511,512,525,532,538,544,545,546,547,548,549,550,551,552,553,554,555,556,557,558,559,560,561,562,563,564,565,566,567,568,569,570,571,572,573,574,575,576,577,578,579,580,581,582,583,584,585,586,587,588,589,590,591,592,593,594,595,596,597,598,599,600,601,602. Among these patients, a recurrence of 1.1% (95% CI 0.8–1.4%) was observed in patients at 12 months, 1.9% (95% CI 1.4–2.4%) at 24 months, and 7.9% (95% CI 6.4–9.4%) at 60 months (Fig. 10).
Recurrence free outcome as a function of follow-up time of patients treated with other flap techniques. Data presented are for RCTs only and for all available studies. Numbers of patients included in the analysis are indicated at 12, 24, 60, and 120 months. Dashed lines indicate 95% confidence intervals.
Recurrence in marsupialisation
Data on recurrence and follow-up times pertaining to 343 patients treated for PSD by marsupialisation were extracted from 8 RCTs17,18,30,47,96,101,603,604. Among these patients, a recurrence of 1.0% (95% CI 0.0–2.3%) was observed in patients at 12 months and 14.3% (95% CI 0.0–30.3%) at 24 months.
Data on recurrence and follow-up times pertaining to 3,207 patients treated for PSD by other flap techniques were extracted from 55 additional non-RCTs4,108,109,115,129,132,133,137,143,163,170,171,177,188,190,193,200,204,215,218,224,230,245,272,279,294,303,313,315,317,318,336,352,358,363,369,593,605,606,607,608,609,610,611,612,613,614,615,616,617,618,619,620,621,622. Among these patients, a recurrence of 1.8% (95% CI 1.2–2.3%) was observed in patients at 12 months, 5.6% (95% CI 4.5–6.7%) at 24 months, 9.4% (95% CI 7.6–11.1%) at 60 months, and 16.3% (95% CI 11.8–20.9%) at 120 months (Supplementary Fig. 1).
Recurrence in limited excision
Data on recurrence and follow-up times pertaining to 384 patients treated for PSD by limited excision were extracted from 5 RCTs29,50,105,604,623. Among these patients, a recurrence of 1.3% (95% CI 0.0–2.9%) was observed in patients at 12 months and 1.7% (95% CI 0.0–3.5%) at 24 months.
Data on recurrence and follow-up times pertaining to 6,366 patients treated for PSD by limited excision PSD treatment were extracted from 71 additional non-RCTs52,61,69,72,73,75,81,83,88,94,106,114,119,121,124,125,131,140,142,144,