Review

Presentation of manuscripts for publication in The British Journal of

Br. J. Surg. 1989, Vol. 76, December, 1311-1 31 5

M. Evans

Scarborough Hospital, Scarborough, North Yorkshire, YO12 6QL. UK Correspondence to: M. Evans

Surgery

You don’t write because you want to say something; you write because you’ve got something to say.

F. Scott Fitzgerald

Most surgeons are impatient perfectionists. They have little time to spare for reading outside their subjects, and what reading they do is probably done while travelling, between operations, or late at night. It is perhaps not surprising, therefore, that they are prepared to tolerate - both in their reading and their writing - convoluted prose, sloppy analyses, careless presentations, and unfounded conclusions. A proportion of the manuscripts submitted for publication in The British Journal of Surgery during the past few months contained one or more of these defects.

Some of the examples were minor - for example, miscalculation of percentages, spelling mistakes and the use of unexplained abbreviations. Some, however, were more serious and could have undermined the editors’ determination to maintain the highest standards of ethical and scientific integrity and surgical reliability. Some authors did not supply enough information for readers to place any reliance on either their results or their conclusions; some quoted percentages inappropriately, given the smallness of their samples, and some did not differentiate between statistical significance and biological relevance, coming to conclusions that were potentially misleading.

This article is not a criticism of the editors. Their principal tasks are to publish ideas, techniques and trials that are interesting and may have a potential for altering clinical practice, as well as controversial statements and authoritative reviews. As most surgeons are not trained in techniques of presentation it does mean that both scientific and technical editors have to spend a lot of time trying to eliminate errors before the papers are printed; their burden would be lighter if authors took the trouble to submit manuscripts that were free from at least the most obvious solecisms.

In this paper I illustrate some of these points, and suggest remedies for the grossest errors of presentation. I must emphasize that many of the defects were corrected before the papers were published and that my analysis was of the manuscripts.

Major faults in presentation Ethics Most authors reporting controlled trials were careful to point out that either the trial had been approved by their local ethics committee, or the patients had given informed (my italics) consent; the extent of information given, and particularly the way in which the process of randomization was explained to patients, however, was usually not mentioned. This is not of particular moment if the experimental procedure being studied is of no pressing concern to the patient, but it is a matter which must be considered.

Inadequate definitions Several studies, which had the potential for altering clinical practice, were rendered less effective than they might have been because they either omitted, or gave inadequate, definitions of events, methods or end points. Such definitions are particularly important in multicentre studies. For example, Cahill et a/.’ reported a study of sutureless colonic anastomosis using a biofragmentable ring. This was carried out in six countries and the authors stated that: ‘Anastomotic leakage, wound infection and subacute obstruction rates reported are those detected clinically.’ That is all. For all the reader knows one hospital could have defined wound infection as redness around the wound, while another accepted only total breakdown.

Clason et aL3 argued in favour of the centralization of vascular surgery to units with a vascular interest, by comparing morbidity and mortality during two periods of time for patients with acute ischaemia of the lower limb. They did not, however, give full details about the comparability of the two groups for some of the risk factors known to have adverse effects on such patients. It is possible that the improvement in morbidity between the two periods could have been caused by an imbalance of the proportions of smokers, or diabetics, or older patients, in one of the groups.

Sarin and Lightwood4 reported an audit or 66 upper and 65 lower gastrointestinal anastomoses constructed with a continuous single layer polyglycolic acid suture. Their complication rates were acceptable, but they failed to define what they meant by wound infection and anastomotic breakdown. Readers might also have appreciated reference to earlier experimental studies of healing after single layer continuous suturing of the colon5.

It is a habit among authors who have made a study of a subject to assume that everybody else knows as much about it as they do. Indeed that probably applies also to the referees of papers, as they have been chosen by the editors because of their special interest. It would have helped general readers, however, to understand the paper by Fisher et a1.6, had they been told what the ‘functional score’ was, and the paper by Ashley et al.’ would have been clearer if ‘Bloom’s grade’ had been explained.

Retrospective studies are useful, particularly when rare diseases or uncommon operations are reported. They are marred, however, if the method of acquiring the data is not mentioned. It is a brave man who states that he studied all patients with a particular ~ondition’.~; data collected for administrative purposes are well known to be inadequate and inaccurate”, and audits based on these data are seldom complete’ ’. Type 111 errors Type 111 errors were first described by Condon” who defined them as ways in which ‘the conclusions drawn are not supported by the data presented’. Murray et ~ 1 . ’ ~ implied in the first sentence of their Discussion that their technique of ultrasonic

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Presentation of manuscripts: M. Evans

shock wave disintegration of gall stones was clinically useful; what they had actually shown was that they had fragmented 55 stones in the laboratory at wave lengths that had been shown to be safe (in rats).

Taylor and MorrisI4 committed a Type 11 and a Type 111 error when they referred to a trend (‘Praziquantel alone showed a trend to being more effective [in gerbils] than albendazole at reducing the number of [hydatid] cysts’). What they really meant was that they had not studied enough gerbils to prove or disprove the null hypothesis, and they failed to emphasize that gerbils may react differently from people.

Several authors equated statistical significance with clinical relevance or biological importance. Some journals now require that confidence intervals are stated instead of (or as well as) P values to minimize this error, but the idea that ‘P< 0.05 =the truth’ is firmly ingrained. For example, Fisher et aL6 claimed that 13 constipated patients who were improved by operation (we are not told what operation) had lower preoperative anxiety scores and lower depression scores than eight similar patients who were not improved. Despite achieving statistical significance ( P < 0.05 and P < 0.02, respectively) the overlaps between the groups (scores 3 to 14 compared with 10 to 19, and 2 to 12 compared with 5 to 11) were such that it is obvious that there were no determinant differences between the groups for either score. There is also a move by some statistical advisers to ban the use ofthe abbreviation ‘NS’ on the grounds that the idea that ‘NS =not significant’ therefore ‘not so’ is as bad as ‘ P <0,05 =the truth’.

Leahy” deserves credit for putting forward a new technique (laparoscopic appendicectomy) that can reduce the length of time spent in hospital after operation. We are told that the patients were generally fit to leave hospital the day after operation, and that they returned to work or normal activities within a week. All well and good had he left it there, but in his Discussion he stated that: ‘The absence of postoperative adhesions is important especially in female patients.’ This is a far reaching conclusion on the experience of four patients, neither the sex nor the length of follow-up of whom are mentioned. Adhesions are less formidable after laparoscopic sterilization than after laparotomy, but it is by no means certain that this will also be the case after appendicectomy.

Moving up the gastrointestinal tract, and also into the fashionable area of allotting ‘scores’ to patients’ degrees of risk, Schein and GecelterI6 maintained that it is possible to use the APACHE I1 score to stratify patients with upper gastrointestinal bleeding on admission to hospital into high and low risk groups so that the best treatment can be chosen for each patient. Their survey was carried out retrospectively (though we are told the method by which the information was garnered) and the conclusions were not validated prospectively in a comparable group of patients. How many methods and ideas that seemed proved by a retrospective survey have bitten the dust when subjected to the objectivity of a prospective validation? Not only that, but Knaus himself would be the first to admit that APACHE I1 was not designed to stratify individual patients before operation; it was designed to allow comparison of the results of treatment within single intensive care units, or among those in different hospitals. In addition, I suspect that there are few hospitals in which a surgeon can rely on getting a comparatively complicated form filled in (including results of measurements of white cell count and serum concentrations of haemoglobin, creatinine, sodium, and potassium, as well as blood gas analyses) in ‘under half an hour’.

I have already mentioned the multicentre trial by Cahill et al.’ (of three methods of large bowel anastomosis) as being flawed by its lack of definitions. Among their conclusions was that: ‘Adequacy of bowel preparation was reported as excellent or good in 84 per cent of cases, and as poor in only 3 per cent, with no difference between the groups.’ To illustrate this they showed a table (Table4) in which the numbers of patients receiving each type of bowel preparation (mechanical

[unexplained], laxative, and enema) are given, as are the numbers receiving antibiotics [unspecified] and the route of administration (systemic or oral). What is not stated is how many patients received any particular combination or combinations of bowel preparation. It is possible from the table to deduce that 11 of 101 patients (10.9percent), six of 16 patients (38 per cent) and five of 85 patients (6per cent) in the three groups, respectively, did not receive any antibiotics at all. It is, therefore, possible that the degree of bacterial contamination differed significantly among the groups, bringing into question an important aspect of their comparability that is not covered by Table1 (Patient details), but which could have had a profound influence on the results of the trial.

Again concerning operations on the large bowel, Horgan et a1.I7 concluded that anal sphincter pressures were reduced after low anterior resection and that this reduction was caused by direct injury to the internal sphincter. In Table2 they give the preoperative measurement ~ we are not told if it is mean (standard deviation) or mean (standard error) - as 67(4), the measurement 10 days after operation as 51(4), and the measurement 6 months later as 53(5). In Tuble2, however, the preanaesthetic value is given as 55(6); it is only in the text that it is disclosed that this value was obtained after premedication with a benzodiazepine. It does not differ significantly from the value 6 months after operation.

The last example of a Type I11 error is from Bird et al.” who suggested that: . . . ‘measurement of serum phospholipase A, activity may provide a simple test for the early identification of most patients with severe acute pancreatitis.’ It may well do so, but the argument would have been more convincing had they compared the prognostic value of the test with the clinical outcome rather than with the results of another predictive test (Ranson) which, though it may be the best we have, is recognized as being less than perfect.

Inappropriate manipulation of numbers I shall restrict myself to noting some of the more obvious statistical errors, as the topic has been reviewed by Murray” and I commend his paper. One of the most common ways in which authors manipulated numbers inappropriately was by using percentages in reporting their results. For example, Ball et al.” stated that: %percent of patients over 70 who died had a preoperative blood urea above 15mmol/l’. This sounds an enormous number, but study of the tables and methods shows that it means seven out of eight patients. Levy et aLzo do give total numbers for their main groups, but give only percentages for morbidity and mortality within subgroups so that it is impossible to tell how many patients they are writing about in particular parts of the paper.

To take the use of percentages to its most ridiculous extreme, Kerin et al.” referred to 3.5 per cent of 46 patients - this is 1.6 patients. Taberner et al.” wrote that of 14 patients in one group, 7.1 percent were male, when what they meant was that there was one man. It is a convention of scientific writing that percentages should not be used at all if the total number is less than 25, they should be given in whole numbers if the total number is between 25 and 100, and only if the total number is greater than 100, may figures be given to one decimal place - and only one.

Percentages have their place, which is to compare one series with another. I fail to see the point of hiding raw data behind percentages, though authors may feel that publication of these calculations is expected of them. The author has to have the raw data to calculate them in the first place so he is making extra work for himself; this leads to the inevitable and sometimes correct conclusion that he is trying to conceal the small size of his sample. Canivet et al.’ also used misleading percentages; it was not apparent until the data were ‘tortured until they confes~ed’~~ , that the percentage referred to a different number out of a different total on nearly every occasion.

Another common manipulation of numbers was the use of means and standard deviations (or standard errors) instead of

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medians and ranges (or interquartiles) for data that were not normally distributed. Murray” has already pointed this out, but his advice seems to have been unheeded. The standard deviation is a measure of the scatter of observations around the mean. If data are normally distributed, 95percent of the observations will lie within two standard deviations on either side of the mean; if the standard deviation is more than half the mean, therefore, the data are unlikely to be normally distributed. One example of the misuse of means and standard deviations is in the reporting of the length of hospital stay (which is never normally distributed); in several reports the figures seem to show that some patients left hospital before they were admitted.

Stansby and GreatorexZ4 were clearly dealing with skewed distributions when they give the mean (s.d.) time to healing (in weeks) of pilonidal sinuses treated by excision and packing as 13.0 (7.5), range 2 to 37, compared with the time after phenol injection: 8.7 (5.5), range 1 to 23. They then report - despite such an enormous overlap - that this difference is highly significant (P<0.001) using Student’s t test. One of the paradoxically reassuring things about this is that if they had not reported the range the overlap would not have been nearly so obvious.

There seems to be a widely held belief that a paper without P values is unpublishable. It is, however, obvious that some authors are ignorant of the purpose of tests of probability. For example, Pimp1 et felt it necessary to point out that 1 out of 100 was not significantly different from 0 out of 181, and disclosed that P > 0.1.

All active drugs have unwanted side effects and the same may be said of computers. One of these is that they allow easy access to statistical tests that seem to give credence to even the most inadequate data. Fisher et aL6 did a multivariate analysis of 11 variables in 65 patients, and Civalleri et ~ 1 . ~ ~ divided 35 patients first into three subgroups, and then each into a further five subgroups; they then applied statistical tests to the differences, and found that some of them were significant.

I am not sure that one should go as far as one eminent statistician and say that if a study needs sophisticated statistical analysis to prove a point it probably does not have much biological (or clinical) relevance, but I do urge that readers should use their common sense: caveat emptor.

Minor faults in presentation Most of the minor faults in presentation can be attributed to carelessness. The prolific use of abbreviations, usually unnecessary, is not only thoughtless but bad manners. Many readers of The British Journal of Surgery have languages other than English as their mother tongues, and abbreviations confuse rather than help them. For example, CNS to one person means central nervous system, to another, coagulase negative staphylococcus. I came across the abbreviation CT used to mean ‘cytotoxic chemotherapy’ in a paper I was editing for another journal. Common sense tells us that long phrases like enzyme-linked immunosorbent assay (ELISA) may be abbreviated, but should always be spelled out the first time they are used. To abbreviate a term that is used only once or twice is unnecessary: fine needle aspiration biopsy was abbreviated to FNAB by Mitchell et a/. in their Introduction, but mentioned only once morez7. I await with interest the spelled out versions of M-AMSA“ and FUdr26.

Carelessness of expression may cause the reader to be confused about numbers in groups. Michaels et studied: ‘a total of 40 laser procedures ... on 37 legs of 34 patients’. They reported that 13 procedures failed to recanalize the superficial femoral arteries; further on in the same paragraph, however, the number of failures was 5 + 2 + 3 + 4 + 2 + 2 = 18. Authors should take great

care to distinguish among totals, and make it absolutely clear to which they refer.

reported the causes of graft occlusion after aortofemoral bypass for peripheral ischaemia, and offended me by giving their results almost entirely in percentages. They also gave numbers in such a way that they could have referred either to subgroups of the total, or to separate groups in addition to the total. Presentation of the data in tables rather than in the text would have made them easier to follow.

Naylor et

Tables and figures Every table and figure must have a title that requires no reference to the text for the reader to understand what it illustrates. If a table or a figure contains a lot of information a key may have to be included in a brief footnote, but long explanations should appear in the text. Better two simple tables than one complex one. Methods of interpreting scans, for example, should be described in the Patients and methods section, not in the figure legend’ 6 .

Mistakes in diagrams included: the bars representing standard deviations above and below the mean were different lengths3’, the number of dots on a scattergram did not correspond to the number of patients given in the text6, and the increments on the vertical axis of a graph differed by as much as lmmZ9. These mistakes show that the work was not checked adequately when it was returned from the medical art department.

Histograms were used quite often, and while they do have a place (when only an impression of the differences among proportions is important), in many cases, for example Winkler et a1.32, tabulation of the data would have been more informative as well as being easier to understand.

Matters of style Most of the papers accepted by the journal were well written and contained none of the errors I have mentioned. I shall say little about the grammatical mistakes, convoluted sentences and tortuous prose found in a minority of papers. The first are usually corrected by the sub-editors and, concerning the last two, the extent to which style should be imposed by editors is a matter of opinion. Language should be ‘. . . a precision tool, conforming to simple rules and conveying meaning logically’33.

On balance I come down in favour of the imposition of a fairly rigid style, principally because the aim of writing is not only to make yourself understood, but also to make certan that you are not m i s u n d e r ~ t o o d ~ ~ . The British Journal of Surgery favours a more liberal approach to stylistic matters; nevertheless, nouns should not be used as verbs, verbs as nouns, or adjectives as adverbs. Superfluous words should be cut out. Purists may well be offended by such examples as Karanjia and Giddings3’ ‘Histology of the biopsies’ (‘histological examina- tion of biopsy specimens’) and Mitchell et a/.27 ‘pancreatic mass lesion’ (‘pancreatic mass’). I sympathize with the 23 patients mentioned by Wilson et who ‘will soon achieve obliteration’.

I was pleased to see that only one abstract stated that: ‘The implications . . . are discussed’37. Abstracts on the whole were informative, but there were still a few that were written in the active voice: abstracts should always be in the passive voice because they are often printed without alteration in abstracting journals. Several papers used the words ‘approximate’ and ‘average’ - surely too vague for serious scientific communications - and there was commonly confusion between ‘prevalence’ and ‘incidence’. In a few papers there was a lack of consistency in terminology; to criticize this might be considered nit picking when the terms used were practically synonymous (for example. stricture and stenosis6),

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but carelessness in small matters undermines one's confidence in the authors' ability to deal correctly with large ones. Archy the cockroach could have been describing the philosophy of some medical writers when he wrote3*: 'inever think at all when i writelnobody can do two things at the same timeland do them well'.

This is a personal view, and 1 have no doubt that many will disagree with me. I do feel, however, that good research deserves to be presented well and that good presentation is as much a part of the research as the collection and analysis of the data. I have the impression that too many people submit manuscripts that have not been sufficiently edited, particularly by their senior authors whose help in the final stages of preparation of a manuscript may be perfunctory. This not only detracts from (and sometimes conceals) a valid message, but also reflects no credit on the writers or their critical faculties. We recognize good writing when we see it; let us also recognize that science has the right to be written well.

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Cahill CJ, Betzler M, Grumez JA et al. Sutureless large bowel anastomosis: European experience with the biofragment- able anastomosis ring. Br J Surg 1989; 76: 3447. Clason AE, Stonebridge PA, Duncan AJ et al. Acute ischaemia of the lower limb: the effect of centralizing vascular surgical services on morbidity and mortality. Br JSurg 1989; 76: 592-3. Sarin S, Lightwood RG. Continuous single-layer gastrointestinal anastomosis: a prospective audit. Br J Surg 1989; 76: 493-5. Jiborn H, Ahonen J, Zederfeldt B. Healing of experimental colonic anastomoses. IV. Effect of suture technique on collagen metabolism in the colonic wall. Am J Surg 1980; 139: 406-13. Fisher SE, Breckon K, Andrews HA, Keighley MRB. Psychiatric screening for patients with faecal incontinence or chronic constipation referred for surgical treatment. Br J Surg 1989; 76: 352-5. Ashley S, Royle GT, Corder A et al. Clinical, radiological and cytological diagnosis of breast cancer in young women. Br J Surg 1989; 76: 835-7. Canivet J-L, Damas P, Desaive C, Lamy M. Operative mortality following surgery for colorectal cancer. Br J Surg 1989; 76: 745-7. McQuillan T, Manolas SG, Hayman JA et al. The surgical significance of the bile duct of Luschka. Br JSurg 1989; in press. McColl I. Observations on the quality of surgical care. In: McLachlan G, ed. A question of quality? Roads to assurance in medical care. Oxford: Oxford University Press, 1976: 51-61. Ball ABS, Thomas PA, Evans SJ. Operative mortality after perforated peptic ulcer. Br J Surg 1989; 76: 521-2. Condon RE. Type 111 error. Arch Surg 1986; 121: 877-8. Murray A, Basu R, Fairclough PD, Wood RFM. Gallstone lithotripsy with the pulsed dye laser: in oitro studies. Br J Surg 1989; 76: 457-60. Taylor DH, Morris DL. Combination chemotherapy is more effective in post-spillage prophylaxis for hydatid disease than either albendazole or praziquantel alone. Br J Surg 1989; 76: 954.

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Appleton GVN, Williamson RCN. Hypoplasia of defunctioned rectum. Br J Surg 1989; 76: 787-9. Winkler E, Kaplan 0, Gutman M et al. Role of cholecystostomy in the management of critically ill patients suffering from acute cholecystitis. Br J Surg 1989; 76: 693-5. Layton PR. Grammar from a one-sided view. The Times 1989; June 26: 10 (col. 3). Roberts PD. Plain English: a user's guide, Harmondsworth: Penguin, 1987. Karanjia ND, Giddings AEB. Subclavian arteritis. Br J Surg

Wilson RH, Campbell WJ, Spencer A, Johnston GW. Rigid endoscopy under general anaesthesia is safe for chronic injection sclerotherapy. Br J Surg 1989; 76: 719-21. Allum WH, Powell DJ, McConkey CC, Fielding JWL. Gastric cancer: a 25-year review. Br J Surg 1989; 76: 53540. Marquis D. Archy on the r ad ioh : Archy's 1lfe of Mehitabel. London: Faber and Faber, 1961: 123.

572-5.

1989; 76: 824-5.

Paper accepted 5 September 1989

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