1. Introduction

The aim of the present study was to determine the fate of abstracts presented at the EAU meeting by focusing on the following objectives: assessing the publication rate in peer-reviewed journals, describing the time-course of subsequent full publication, and identifying abstract characteristics associated with publication.

2. Methods

2.2. Assessment of subsequent publication

3. Results

Overall, 1406 abstracts were presented at the EAU 2000 and 2001 meetings, 666 of which were followed by publication in Medline-indexed journals, for a publication rate of 47.3%. The percentage of abstracts published increased significantly from 2000 to 2001 (28.2% versus 71.8% of 666 articles, p<0.001).

Fig. 1. Publication rates after abstract presentation.

Abstracts originated from 39 countries: 74.2% European (n=1044), 11.6% South American (n=164), 7% North American (n=98), and 5.5% Asian (n=78). The country of origin also influenced the likelihood of subsequent publication. There were 30 countries with at least one article subsequently published. More than 15 published abstracts originated from each of 12 countries (Table 1).

Table 1. Publication rates according to Country origin

	Country	No of abstracts	No of published abstracts (%)	Adjusted odds ratio* (95% CI)	P value for adjusted odds ratio
	France	148	62 (41.9)	0.66 (0.37, 0.86)	ns
	Germany	360	168 (46.7)	0.77 (0.35, 0.91)	ns
	Italy	110	52 (47.3)	0.79 (0.31, 1.95)	ns
	Austria	96	46 (47.9)	0.85 (0.40, 1.82)	ns
	Switzerland	66	32 (48.5)	0.84 (0.48, 1.46)	ns
	USA	98	48 (49)	0.89 (0.44, 1.82)	ns
	Belgium	56	28 (50)	0.88 (0.43, 1.77)	ns
	U.K.	128	66 (51.5)	0.90 (0.47, 1.65)	ns
	Finland	26	16 (61.5)	1.22 (0.77, 1.96)	0.036**
	Japan	24	16 (66.7)	1.54 (0.88, 2.32)	0.025**
	The Netherlands	48	34 (70.8)	2.03 (1.26, 3.34)	0.007**
	Greece	22	18 (81.8)	2.7 (1.35, 5.81)	0.005**

ns=not significant; CI=confidential interval.

* Odds ratios adjusted according to study subject and type of research. ** Significant difference between the odds of articles originating form this country being published versus the odds of articles originating form other countries being published.

The mean IF of the journals of publication was 1.95 (SD 0.6). The number of papers published in journals with an IF<1, between 1 and 3, and >3, were 166 (25%), 382 (57%), and 118 (18%), respectively.

When considering the research type, we found that 458 out of 1016 (45%) clinical studies and 208 out of 390 (53.3%) pre-clinical studies were published (p<0.05). Among presented clinical studies, prospective trials were more likely to be published than retrospective assessments (46.5% vs 32.2%, respectively; p<0.05).

In terms of type of presentation, 273 of 548 (49.8%) oral and 393 of 858 (45.8%) poster presentations were published after the meeting. This difference was not statistically significant (p=0.07).

Table 2 presents publication rates based on study subject. Abstracts on UTI, SWL, bladder cancer, laparoscopy, and andrology had the highest publication rates.

Table 2. Publication rates according to study subject

	Subject	No of abstracts (% of total)	No of published abstracts (% of presented)	Adjusted odds ratio (95% CI)	P value for adjusted odds ratio
	Testis cancer	47 (3.3)	10 (21.3)	0.45 (0.11, 2.11)	ns
	Reconstructive urology	102 (7.2)	30 (29.4)	0.73 (0.54, 1.02)	ns
	BPH	136 (9.6)	42 (30.9)	0.59 (0.33, 0.95)	ns
	PCNL	18 (1.3)	6 (33.3)	0.74 (0.53, 1.07)	ns
	TUR	42 (3)	16 (38.1)	1.02 (0.58, 1.88)	ns
	Prostate biopsy	28 (2)	12 (43)	0.84 (0.61, 1.16)	ns
	Incontinence	160 (11.4)	74 (46.2)	0.89 (0.62, 1.24)	ns
	Prostate cancer	325 (23.1)	160 (49.2)	0.99 (0.77, 1.14)	ns
	Ureteroscopy	16 (1.1)	8 (50)	1.02 (0.79, 1.25)	ns
	Others	40 (2.8)	20 (50)	1.11 (0.82, 1.43)	ns
	Renal cancer	74 (5.2)	38 (51.3)	1.18 (0.89, 1.62)	ns
	Andrology	116 (8.2)	62 (53.4)	1.29 (0.86, 2.02)	0.03
	Laparoscopy	84 (6)	46 (54.8)	1.24 (0.80, 1.92)	0.02
	Bladder cancer	176 (12.5)	108 (61.3)	1.23 (0.89, 1.76)	0.04
	ESWL	20 (1.4)	16 (80)	1.57 (1.05, 2.37)	0.03
	UTI	22 (1.5)	18 (82)	1.72 (1.14, 2.63)	0.01
	Total	1406	666 (47.3)

A clearly “sponsored” study was found only in 22 cases (3.3% of the total). Among these, 12 were followed by publication. Because of the small numbers, a significance analysis was not performed on these data.

4. Discussion

Several studies from different medical specialities have analyzed the full publication of abstracts presented at their meetings. The highest proportions of full publication were in the fields of oncology (74%) [11], orthopaedics (64%) [12], and anaesthesiology (50%) [13]. We found that almost one-half of the abstracts presented at the EAU 2000 and 2001 meetings were subsequently published in peer-reviewed journals included in Medline.

In general, reasons for not publishing abstracts are multi-factorial [14]. Because of the marked differences in the peer-review process for a paper for presentation at a scientific meeting and for a manuscript being considered for publication in an indexed journal [15], many accepted abstracts would fail to stand up to rigorous peer review for a journal. In addition, abstract preparation requires only a fraction of the effort that manuscript preparation requires. Emphasizing this point, Dickersin et al. found that the primary reason cited by investigators for failure to publish an abstract was “lack of time” for manuscript preparation [16]. Another factor emerging in the same study was that training programmes pay for travel costs to national meetings for trainees who are presenting abstracts. This practice encourages trainees to prepare abstracts, but without similar rewards for manuscript preparation, their interest in pursuing paper publication diminishes. These observations indicate that publication in a scientific journal is not the ultimate goal of every abstract presentation.

It is possible that some research is only important enough to be presented but does not meet standards for publication. Alternatively, in some cases, the methods or results of studies presented at meetings are flawed, with faults not detected by review committees. Of course, the methodological quality of conference abstracts can be difficult to evaluate [17].

Overall, an author must be actively trying to get the work published; thus, the publication rate could represent the motivation of the author more than the quality of the paper. Scientific societies should therefore persuade authors of accepted abstracts to complete and submit their manuscript for publication. Moreover, according to Weber et al., subsequent publication efforts may be affected by a meeting committee's decision to accept an abstract or not [18]. Because failure to publish completed research affects medical practice, societies should make additional efforts to encourage all investigators to submit for publication, not just those whose abstracts are accepted for presentation.

It has been recently suggested that many, but not all, practitioners and researchers believe IF is a valid indicator of journal quality [19], [20]. We found that 75% of reports were published in peer-reviewed journals with an IF above 1, and the mean IF was almost 2. Such an evaluation has not been done in previous urological reports [4], [5]. One simple explanation for the “low” mean IF is that most urologists seek full publication in “urology” journals, which generally have low IFs. The IFs of only three “urology” journals are now above 3, according to the JCR [10].

It is perhaps a little surprising that more presentations at the European meeting are published in The Journal of Urology than in European Urology. Some of these papers may also have been presented at the AUA meeting, but we did not cross-check with AUA published abstracts. Ng et al. [4] produced the only report on AUA, but they did not mention which journals published the studies. Other major urological journals published most of the remaining papers from our study, whereas “non-urology” journals hosted a limited number.

Previous authors have noted that the vast majority of abstracts resulting in publication in indexed journals are published within 5 years [9]. Similarly to Ng et al. [4], we found that most publications occurred within 2 years of meeting presentation. Rao et al. reached a different conclusion, finding that papers were being published 3 years after presentation at the BAUS meeting [5]. Some editorial boards may disallow the inclusion of abstracts as references if >3 years have elapsed since presentation because the lag renders questionable the scientific validity of the published abstract and its use in clinical practice. The Uniform Requirements for Manuscript Submitted to Biomedical Journals explicitly advises authors to try to avoid using abstracts as references [21].

Among the others, one factor influencing the rate of publication is publication bias, in which positive results tend to be published preferentially over studies with negative findings [22]. Positive-outcome bias is particularly problematic in pooled studies such as meta-analyses, which are increasingly being used in medical research, because it can lead to an overestimation of the degree of the effect [23].

Abstracts reporting on pre-clinical research were more likely to be published, and differences in the quality of conducting and reporting basic research can explain this finding. Moreover, experimental studies are mostly prospective and require careful forethought and planning. Of the clinical trials, prospective studies were more likely to be published than retrospective ones. This trend would have been much more evident if only randomized controlled trials had been considered, as recently suggested by Toma et al. [24].

The frequency of publication of studies in some subjects was markedly higher than that of studies in other subjects. SWL remains a timely topic in urology. Studies on UTI presented at the meetings were few but had a very high publication rate. When considering prostate cancer, we found a large difference between the relative number of abstracts presented on this subject and those subsequently published. This was not the case for bladder cancer, which represented the second most common topic of the presented abstracts and had a high publication rate. The growing role of laparoscopy in urology has been confirmed by our analysis. Not surprisingly, the interest of investigators in the field of andrology is steadily increasing.

Interestingly, we found abstracts mostly originating from Europe, a remarkable difference compared with the frequency originating in America or Asia. Significantly higher publication rates were identified from Greece, The Netherlands, Japan, and Finland. On the other hand, Germany, France, Italy, and the UK presented a much higher number of abstracts at the meetings, although their publication rates were found to be slightly lower than those of the previously mentioned countries.

Similarly to Ng et al. [4] and Rao et al. [5], we found no significant difference between the publication rates of oral versus poster presentations. Therefore, the common belief that papers presented as podium presentations are of higher quality than those given as posters was not confirmed.

Our study has some limitations. We searched for published articles in a single database (Medline) by using a single search engine (PubMed), and some published manuscripts might have been overlooked or published in non-Medline journals. We are aware that it might have been less constraining to use other major engines (such as Embase or Cochrane Library). Nevertheless, we feel that it is unlikely that a significant difference would have been found; for example, in their Medline search for articles on medical imaging, Berry et al. found that 94% of target references were identified [25].

Although a search based on authors’ last names has been used previously in such studies, to our knowledge its efficiency has not been assessed. Errors in the search may occur owing to the misspelling of the first author's last name or the fact that the first author of the abstract is not an author of the resulting full article. We minimized these risks by repeating unfruitful searches using the last name of the second author and, if necessary, that of the senior author. Thus, the observed publication rate is likely to be only slightly lower than the actual publication rate.

As stated in the methods section, published papers that were nearly identical to the abstracts in title, hypothesis, and study design were included as a match. We did not perform a more in-depth comparison between the study presented at the meetings and those in peer-reviewed journals. Such an evaluation has been done by Dasit et al in a recent paper [26]. They found that both study sample and first author frequently changed in the transition from meeting abstract to full-length journal article for the studies presented at the European Congress of Radiology. Their findings suggested that an increase in the size of the series may be related to the completion of the research work, while a decrease in the size can indicate a streamlining of the series to increase the quality of the paper. In terms of the authors’ position, it seems reasonable that in papers of greater scientific quality and interest, the most relevant investigator wishes to be the first

Overall, the idea that our findings could be considered as a “mirror” of the current status of urology in Europe is questionable, primarily because of the different technical and philosophical innovations both in EAU and in the European Urology Journal over the last few years [8], [27].

5. Conclusions

Almost half of the studies originally presented at the 2000 and 2001 EAU meetings were subsequently published in Medline-indexed journals. Articles were published less than 2 years after the meeting in 80% of cases. The publication rate differed significantly according to the abstract country of origin, the study subject, and the research type. More articles were published in The Journal of Urology and European Urology than in other identified journals.

Editorial Comment

Mark J. Speakman

If there is a correlation between the quality of the work presented and the chance of it being published, it implies that the standard of scientific presentation at the European meeting may be at least as high as that at the American Urological Association (AUA) and other international meetings. Although this is very encouraging, a reasonable caveat should be that the period of follow-up here after the European Association meeting was 5 yr compared with the 2- and 3-yr follow-up after the rather lower AUA (38%) and BAUS (42%) publication rates. In this study, almost 5% of papers were published in each of the three 6-mo periods after 3 yr (Fig. 1).

It is interesting that presentations from Finland, Japan, The Netherlands, and Greece were statistically more likely to be published that others, but this may be more influenced by the smaller volumes from these countries. More interesting perhaps was the fact that presentations on andrology, laparoscopy, and particularly extracorporeal shock wave lithotripsy (ESWL) and urinary tract infection (UTI) were more likely to be published that those in the other 11 disease areas. It is no surprise that basic science and prospective studies were more likely to be published than clinical and retrospective trials.

Perhaps the real questions are why do some authors fail to publish their research and what are the barriers to publication? Other studies have suggested that lack of available time, ongoing studies, difficulties with coauthors, and relocation of authors are major barriers to publication; but without knowing how many papers were subsequently written up but then failed peer review, it is difficult to generalise. It is this latter group that may have been scientifically invalid at peer review. Finally, should there be a formal warning that research from annual meetings should not be introduced in general clinical practice until it has undergone the more formal and detailed peer review of submission for publication?

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Riccardo Autorino, Giuseppe Quarto, Giuseppe Di Lorenzo, Marco De Sio, Rocco Damiano

Clinica Urologica, Seconda Università degli Studi, Napoli, Italy
Dip. di Oncologia Molecolare e Clinica, Università Federico II, Napoli, Italy
Cattedra di Urologia, Università Magna Graecia, Catanzaro, Italy

Accepted 16 October 2006 published online 30 October 2006.

European Urology Volume 51, Issue 3, Pages 833-840, March 2007

UroToday.com Laproscopic and Robotic Section

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