Skin Cancer Excision Is More Efficient and Cost Effectivein a Specialist Secondary Care Service.

Aim To compare the relative efficiencies of skin excisions in primary and secondary care. Methods We compared the benign: malignant ratio for specimens referred by General Practice, General Surgery and the Skin Cancer Service to the regional pathology laboratory over one month. We used cost minimization analysis to compare the relative efficiencies of the services. Results 620 excisions were received: 139 from General Practice, 118 from General Surgery and 363 from the Skin Cancer Service. The number (%) of malignant lesions was 13 (9.4%) from General Practice, 18 (15.2%) from General Surgery and 137 (37.7%) from the Skin Cancer Service. Excision was cheaper in General Practice at €84.58 as compared to €97.49 in the hospital day surgical unit. However, the cost per malignant lesion excised was €1779.80 in general practice versus €381.78 in the Skin Cancer Service. Conclusion Our results indicate that moving skin cancer treatment to General Practice may result in an excess of benign excisions and therefore be both less efficient and less cost effective.

Duration of action of hypertonic saline on mucociliary clearance in the normal lung.

Inhalation of hypertonic saline (HS) acutely enhances mucociliary clearance (MC) in both health and disease. In patients with cystic fibrosis (CF), repeated use of HS causes a sustained improvement in MC as well as clinical benefit. The pharmacodynamic duration of activity on MC may be an important determinant of its therapeutic potential in other airways diseases. Before moving toward testing the clinical benefits of HS for non-CF indications, we sought to assess the duration of pharmacodynamic effects of HS in healthy subjects by performing radiotracer clearance studies at baseline, 30-min post-HS administration, and 4-h post-HS administration. Indeed, acceleration of MC was observed when measured 30 min after HS inhalation. This acceleration was most pronounced in the first 30 min after inhaling the radiotracer in the central lung region (mean Ave30Clr = 15.5 vs. 8.6% for 30-min post-HS treatment vs. mean baseline, respectively, P < 0.005), suggesting that acute HS effects were greatest in the larger bronchial airways. In contrast, when MC was measured 4 h after HS administration, all indices of central lung region MC were slower than at baseline: Ave30Clr = 5.9% vs. 8.6% (P = 0.10); Ave90Clr = 12.4% vs. 16.8% (P < 0.05); clearance through 3 h = 29.4 vs. 43.7% (P < 0.002); and clearance through 6 h = 39.4 vs. 50.2% (P < 0.02). This apparent slowing of MC in healthy subjects 4-h post-HS administration may reflect depletion of airway mucus following acute HS administration.

Regional deposition and regional ventilation during inhalation of pentamidine.

In most patients, the deposition of aerosolized pentamidine (AP) is less in the apex of the lung relative to the base. As the apex of the lung is relatively less ventilated than the base, it is possible that reduced regional ventilation may explain the inhomogeneity in regional drug deposition. The purpose of this study was to measure the relationship between regional deposition of AP and regional ventilation, and the influence of particle size and airway caliber on this relationship. Ten subjects with HIV infection who were receiving prophylaxis with AP were recruited. Using krypton (81mKr), we measured regional ventilation during treatment with AP, labeled with 99mTc. Two nebulizers were used (Respirgard II and Fisoneb) that produced particles of different size. In addition, patients were studied with and without a bronchodilator because changes in airway geometry can affect sites of particle deposition. There was no significant correlation between regional ventilation and regional particle deposition (r = 0.00, linear regression). Particle deposition in the upper lobes relative to the lower lobes was less than would be predicted by regional ventilation, by a ratio of 0.84 +/- 0.03 (mean +/- SE). Using two-way analysis of variance (ANOVA), the upper to lower zone deposition pattern was not affected by either nebulizer or by the use of albuterol. The Fisoneb had significantly more central deposition relative to the jet nebulizer (mean +/- SE, skC/P: Fisoneb 1.3 +/- 0.1, Respirgard 1.1 +/- 0.1, p = 0.005, two-way ANOVA). The use of a bronchodilator did not significantly affect the central/peripheral deposition pattern. We conclude that differences in deposition between upper and lower lung regions are not accounted for simply by differences in regional ventilation in patients undergoing prophylaxis with AP. In assessing the cause of regional inhomogeneities of pharmaceutical aerosol deposition (and in devising strategies to achieve more uniform distribution), regional ventilation should be measured directly rather than be inferred from the deposition pattern of the aerosol.

Exposure of health care workers to aerosolized pentamidine.

In patients, urinary levels of pentamidine have been shown to reflect pulmonary deposition of aerosolized drug. Using urinary levels and air filter samples, we assessed factors responsible for health care worker (HCW) exposure. We measured serial urine samples in HCWs who administered aerosol pentamidine over an 11-month period and compared them with serial urine levels measured over 30 days in a normal volunteer in whose lungs a known amount of pentamidine (3.39 mg) had been deposited. Ambient exposure to pentamidine was determined by continuous high volume air sampling in the treatment room during routine therapy. In addition, the amount of pentamidine released by six HIV-positive subjects, performing tidal breathing with a Respirgard II nebulizer in an airtight booth, was measured by extracting air from the booth through a filter. The effect of adding noseclips, of coughing (with nebulizer shut down), and of removing the nebulizer from the patient's mouth without turning it off, were determined. Pentamidine in the urine of the normal volunteer reached a peak concentration of 9.5 ng/mg creatinine/ml and was detectable for 30 days following the exposure. In HCWs, pentamidine was detected intermittently in four of five individuals with levels as high as 18.2 ng/mg creatinine/ml. Samples of ambient treatment room air indicated small daily releases of pentamidine (0.013 +/- 0.02 mg per patient treated), but simultaneous urine levels in HCWs were negative. The data from the airtight booth revealed that removing the nebulizer from a patient's mouth without turning it off caused a 360-fold increased in pentamidine release compared to tidal breathing. Coughing resulted in a 6.9 (range 0.9-14.2)-fold increase in release, while the addition of noseclips had no significant effect. The pattern of intermittently positive urine tests and the low levels of ambient pentamidine detected in the air of the treatment room suggest that HCWs are being exposed to episodic but high concentrations of pentamidine. High level exposure is most likely to occur during treatment interruptions which are usually precipitated by coughing episodes. Because of the intermittent pattern of exposure and slow clearance of pentamidine, urine assay is useful for detecting high intermittent exposure. Random air sampling is a sensitive indicator of low level exposures but may not detect episodic high level releases.

Changing patterns of aerosol deposition during methacholine bronchoprovocation.

During bronchoprovocation testing with methacholine, induced changes in airway geometry are known to affect sites of drug deposition. However, it is not known if changes in these sites determine measured responsiveness. We assessed the importance of sites of deposition as determinants of reactivity by comparing particle behavior in two subject groups with and without hyperresponsiveness. By administering radiolabeled aerosols of similar aerodynamic characteristics to methacholine aerosol, we measured the deposition pattern in terms of the specific central to peripheral ratio (sC/P) before and after methacholine inhalation (sC/P1 and sC/P2, respectively) and thereby quantified the changes in deposition sites that occur during the course of a typical bronchoprovocation test. Subjects whose FEV1 decreased by 20 percent or greater were classified as methacholine responsive (MR; nine subjects), and the remainder were classified as non-methacholine responsive (NMR; seven subjects). The two groups had similar baseline FEV1 percent predicted (FEV1 percent) and initial deposition patterns (sC/P1) with particles depositing primarily in peripheral airways (mean +/- SE; sC/P1 1.43 +/- 0.070 and 1.39 +/- 0.65, MR and NMR, respectively, p = NS). Following methacholine inhalation, the deposition pattern changes markedly for all subjects with particles depositing primarily in central airways (sC/P2 2.58 +/- 0.24, p = 0.001, and 2.15 +/- 0.22, p = 0.001 from baseline, p = NS between groups) By definition, the MR subjects had a significantly greater change in FEV1 than the NMR subjects. Preferential deposition in central airways occurs in all subjects during bronchoprovocation testing and does not significantly determine methacholine responsiveness.

Tracheal aspirates in long-term mechanically ventilated patients. A human model of gram-negative infection and airway inflammation.

It is well known that patients requiring long-term mechanical ventilation and tracheostomy have nearly universal airway colonization with Gram-negative organisms. However, useful parameters to objectively describe the airway inflammation associated with airway instrumentation and colonization have not been well define. In our respiratory care unit, patients who are medically stable except for ventilator dependence are readily available for longitudinal assessment of airway secretions and therefore provide a unique population for studying airway inflammation and infection. To quantitate production of respiratory secretions, we instituted a uniform protocol of suctioning over a 6-h period. Further, we devised a method of dilution and homogenization of tracheal aspirates that permits reproducible intrasample total cell counts (coefficient of variation, 4.6%). With these techniques, patients were then studied serially over a 4- to 7-week period. Total cell count, inflammatory cell differential, and two indices of airway inflammation, human neutrophil elastase (HLE) and soluble-intercellular adhesion molecule-1 (sICAM-1) studied in the sol phase of secretions were monitored. The mean total cell count was 42.2 x 10(6) cells per gram of secretions when patients were clinically stable and not receiving antibiotics. The average differential was neutrophils 69.9%, macrophages 26.9%, and lymphocytes 2.8%. Mean active HLE was 35.6 micrograms/mL and mean sICAM-1 was 83 ng/mL. Six patients during the period of observation received intravenous oral or aerosolized antibiotics for tracheobronchitis. A threefold drop in volume of secretions was measured (p < 0.018). The total cell count and percent neutrophils decreased from 76.4 x 10(6)/g of sputum to 54.9 x 10(6) and 72.2 to 54.9%, respectively. While these changes were not statistically significant, the absolute number of airway neutrophils over the 6 h decreased sevenfold (p < 0.014). Similarly sICAM-1 burden (micrograms per 6-h period) also decreased significantly (p < 0.034). These patients provide a unique human model for future studies specifically designed to assess the effect of novel modalities of anti-inflammatory and antimicrobial agents on respiratory secretions.

Lobar pentamidine levels and Pneumocystis carinii pneumonia following aerosolized pentamidine.

Recent studies have suggested that failure of pentamidine prophylaxis against Pneumocystis carinii pneumonia (PCP) may be due to reduced deposition of pentamidine in the upper lobes. In this study, we performed bronchoalveolar lavage from the apical segment of the upper lobe and the middle lobe in 51 HIV-positive patients, all of whom were receiving prophylaxis with aerosolized pentamidine, who had presented with acute respiratory symptoms. Lavage fluid from each lobe was assayed for pentamidine using high-performance liquid chromatography (HPLC). The number of clusters of P carinii were counted after staining with a Wright-Giemsa stain. The patients were subclassified as PCP-positive (32 patients) and PCP-negative (19 patients) on the basis of the presence/absence of P carinii clusters in their BAL fluid. The concentration of pentamidine in the upper lobe compared with the middle lobe was no different (using paired Student's t tests) for either PCP-positive patients or PCP-negative patients. In comparing the positive with the negative subjects, using unpaired Student's t test, there was no difference in the concentration of pentamidine in the upper lobe or the middle lobe. For PCP-positive patients, the numbers of P carinii clusters were on average higher in the upper lobes (mean +/- SD: upper = 14.9 +/- 16.6, middle 7.5 +/- 10.8, p = 0.013, paired Student's t test), but there was no correlation between lobar P carinii cluster counts and pentamidine levels. We conclude that the absence of a relationship between cluster count and pentamidine level, the similarity in regional pentamidine levels between upper and middle lobes, as well as the similarity in pentamidine levels between the PCP-positive and PCP-negative groups indicate that the regional dose of pentamidine is not the determining factor as to whether aerosolized pentamidine prophylaxis will succeed or fail.

Regional impairment of mucociliary clearance in chronic obstructive pulmonary disease.

Asthmatic subjects with tidal expiratory flow limitation have mucociliary clearance (MC) impairment in central airways. Because tidal flow limitation develops in COPD, it is possible that regional MC in these patients also may be affected. We tested this hypothesis by measuring MC in the presence or absence of flow limitations. Patients with COPD and chronic flow limitation were compared with non-flow-limited normal volunteers. Deposition was normalized for regional lung volume and expressed as the specific central to peripheral (sC/P) ratio. In COPD subjects, clearance from the whole lung and central airways was significantly different from that of normal subjects after 20 min of observation. In the peripheral airways, there were no significant differences between COPD and normal subjects. An alternative analysis of regional MC indicated patients retained particles in central airways while normal subjects, with intact MC, emptied central airways. Thus, COPD subjects with tidal expiratory flow limitation have impaired MC in their central airways.

Budesonide affects allergic mucociliary dysfunction.

Airway inflammation characterized by neutrophils and free elastase contributes to allergic mucociliary dysfunction. Glucocorticosteroids are the most important anti-inflammatory agents used in the treatment of asthma, but their effect on allergic mucociliary dysfunction is not known. Therefore, we assessed both the prophylactic and therapeutic effects of the glucocorticosteroid budesonide on antigen-induced mucociliary dysfunction in sheep. Tracheal mucus velocity (TMV), a marker of mucociliary clearance, was measured by using a roentgenographic technique. When budesonide was administered either 30 min before or 1 h after airway challenge with Ascaris suum, the antigen-induced fall in TMV at 6 h was prevented. The effects on TMV at 8 and 24 h after challenge were also determined when budesonide and, for comparative purposes, alpha1-protease inhibitor were given 6 h after antigen challenge. Budesonide treatment improved TMV at 8 h, but TMV was not significantly different from antigen alone at 24 h. Treatment with alpha1-protease inhibitor, however, caused only a significant reversal of the antigen-induced fall in TMV at 24 h after challenge; this indicates a more prolonged effect than budesonide. Our results suggest that antiproteases may have a potential role as a therapeutic approach to mucociliary dysfunction in asthma and provide evidence for another means by which glucocorticosteroids contribute to the control of the disease.

Aerosolization of P2Y(2)-receptor agonists enhances mucociliary clearance in sheep.

The purpose of this study was to determine whether aerosolized INS316 (UTP) stimulates lung mucociliary clearance (MCC) in sheep and, if so, to compare its effects with INS365, a novel P2Y(2)-receptor agonist. In the first series of studies, we used a previously described roentgenographic technique to measure tracheal mucus velocity (TMV), an index of MCC, before and for 4 h after aerosolization of INS316 (10(-1) M and 10(-2) M) and INS365 (10(-1) M and 10(-2) M), or normal saline in a randomized crossover fashion (n = 6). In a second series of studies, we compared the ability of these agents to enhance total lung clearance. For these tests, the clearance of inhaled technetium-labeled human serum albumin was measured serially over a 2-h period after aerosolization of 10(-1) M concentration of each agent (n = 7). Aerosolization of both P2Y(2)-receptor agonists induced significant dose-related increases in TMV (P < 0.05) compared with saline. The greatest increase in TMV was observed between 15 and 30 min after drug treatment. The highest dose (10(-1) M) of INS316 produced a greater overall stimulation of TMV than did INS365 (10(-1) M). Both compounds, compared with saline, induced a significant increase in MCC (P < 0.05) within 20 min of treatment. This enhancement in MCC began to plateau at 60 min. Although the response to INS316 started earlier, there was no significant difference between the clearance curves for the two compounds. We conclude that inhaled P2Y(2)-receptor agonists can increase lung MCC in sheep and that for P2Y(2)-receptor stimulation TMV accurately reflects changes in whole lung MCC.

Progressive multifocal leukoencephalopathy-remission with cytarabine.

A 51-year-old woman who was in complete remission from non-Hodgkin's lymphoma, developed a rapidly progressive dementia. Progressive multifocal leukoencephalopathy (PML) was diagnosed on the basis of a rising antibody titre to JC polyomavirus in cerebro-spinal fluid and serum and the presence of diffuse white matter changes on magnetic resonance imaging. She was treated initially with intravenous cytarabine and showed minimal improvement. Rapid improvement occurred when intrathecal cytarabine was added and the patient is in complete remission from both lymphoma and PML 20 months later.

Inhaled antimicrobial therapy: from cystic fibrosis to the flu.

Recent controlled clinical trials have confirmed the usefulness of aerosolized tobramycin in cystic fibrosis and have emphasized the importance of ensuring adequate lung delivery of inhaled antimicrobials. For purulent tracheobronchitis associated with prolonged mechanical ventilation it has recently been established that it is possible to deliver substantial and measurable doses of medications to the airway via aerosolization, but controlled studies are needed to determine the efficacy and safety of inhaled antibiotic therapy in this setting. However, prophylactic aerosolized antibiotic therapy in an intensive care unit setting may be counterproductive. Aerosolized pentamidine continues to provide prophylaxis against PCP in a substantial minority of subjects with human immunodeficiency virus infection who are intolerant of oral agents. The effectiveness of aerosolized amphotericin B as prophylaxis against aspergillosis in neutropenic patients needs to be evaluated in a large clinical trial. Zanamivir, an inhibitor of neuraminidase, delivered via inhalation, shows promise in the treatment of uncomplicated influenza infection, but more data are needed on its effectiveness and safety in patients with preexisting respiratory disease. The development of new chemical entities, more efficient delivery systems, and more precise measurement of dose-response and regional pulmonary drug distribution of inhaled antimicrobials suggest that this somewhat neglected topic in therapeutics may be about to receive an increased degree of attention.

Effect of nebulizer configuration on delivery of aerosolized tobramycin.

Differences in the reported efficacy of aerosolized aminoglycosides may be due, in part, to differences in aerosol delivery. Optimization of delivery systems of bench testing of nebulizers in a manner that simulates clinical conditions can lead to enhanced lung deposition in subsequent clinical studies. In the present study, we assessed the effects of varying nebulizer configuration on the performance of ultrasonic and jet nebulizers. Tobramycin was mixed with a radiotracer (99mTc) to facilitate measurement of nebulizer output and particle size. A piston ventilator provided a simulated breathing pattern, and the dose delivered to a filter corresponded to what would have been inhaled by a patient (percentage of nebulizer charge inhaled). Particle size was measured using a cascade impactor, sampling at 1 L/min. An ultrasonic nebulizer (Ultra-Neb; DeVilbiss, Somerset, PA), ventilated at 20 breaths per minute, charged with 600 mg of tobramycin (in 30-mL volume) and fitted with its standard tubing, was tested with and without the addition of one-way valves to the inspiratory and expiratory ports of the mouthpiece. In order to assess the degree of environmental contamination associated with jet nebulizer therapy, a filter was placed at the expiratory port of all jet nebulizer experiments. The addition of the valves reduced the percentage of charge inhaled from a mean +/- standard deviation (SD) of 29.2% +/- 1.4% to 7.6% +/- 2.3% and reduced mass median aerodynamic diameter [MMAD (sigma g) from 4.3 microns (2.1) to 1.45 microns (1.65)]. A Circulaire (Westmed, Tucson, AZ) jet nebulizer (7 L/min flow, 50 pounds per square inch gauge (psig), 20 breaths per minute, containing 160 mg of tobramycin in a 4-mL volume) was tested in two configurations: using a plain T-piece and using a valved inflatable aerosol chamber. The use of the holding chamber resulted in an almost twofold reduction in MMAD [MMAD (sigma g) = 2.45 microns (2.0); T-piece; 1.25 microns (2.0), holding chamber]. A slight reduction in the percentage of nebulizer charge inhaled using the holding chamber, compared to the plain T-piece, was not statistically significant (mean +/- SD of percentage inhaled with holding chamber = 20.8% +/- 1.6%; with T-piece = 23.6% +/- 0.5%). With both the jet and ultrasonic nebulizers, breathing frequency influenced percentage inhaled, with a higher percentage inhaled at 20 breaths per minute compared to 15 breaths per minute. The use of the plain T-piece at 20 breaths per minute was associated with more environmental contamination than the use of the holding chamber with the same breathing pattern (26.7% +/- 1.0%, T-piece; 4.5% +/- 0.3%, holding chamber, P < 0.0001). We conclude that nebulizer configuration can potentially affect both the amount of aerosol inhaled and the particle size, and needs to be specified precisely in treatment protocols.

Bench testing of nebulizers: a comparison of three methods.

Although nebulizers can vary widely in performance, there is no uniformly accepted method for bench testing these devices. In the present study, we compared three bench methods of measuring the performance of three commercial jet nebulizers (Whisper Jet [WJ; Marquest Medical, Englewood, CO], Sidestream [SS; Marquest Medical], and Vixone [VO; Westmed, Tucson, AZ] to assess the impact of the method of testing on reported nebulizer performance. Each nebulizer was charged with 3 mL of albuterol mixed with a radiotracer (technetium [99mTc]), and the radioactivity captured on a paper filter was expressed as a percentage of the nebulizer charge (% delivered). The nebulizers were tested with and without duplication of spontaneous respiration by a piston pump (spontaneous respiration and standing cloud methods, respectively). The nebulizers were also tested using a model of mechanical ventilation (mechanical ventilation method). For all three devices, the addition of the standardized breathing pattern significantly reduced the % delivered with all three nebulizers compared with the standing cloud method. For the standing cloud method, the presence of the T-piece/mouth-piece significantly reduced the % delivered with the WJ but not with the other two devices. The mechanical ventilation method had the lowest % delivered for all three devices. The magnitude of the differences between nebulizers varied with duration of treatment. The findings of this study emphasize the importance of bench testing that duplicates intended clinical usage, because significant differences in nebulizer performance may be manifested under certain clinical conditions but not under others.

Effects of unilateral bronchoconstriction on distribution of aerosols in ovine airways.

The purpose of the study was to assess the effect of unilateral bronchoconstriction on the deposition patterns of aerosolized particles in a sheep model. Unilateral bronchoconstriction was induced in intubated conscious sheep by placing a protective, obstructing balloon catheter in either main bronchus, prior to administration of aerosolized carbachol at a dose that increased pulmonary resistance by 200-400% above baseline. The catheter was then removed and the animals were positioned under a gamma camera. An equilibrium image was obtained with xenon (133Xe), to determine a lung outline that was used to calculate the proportion of counts in each lung. Aerosols, labeled with technetium (99mTc) and generated by two jet nebulizers, were inhaled tidally by the sheep in serial experiments. (For nebulizer A, mass median aerodynamic diameter [MMAD] = 0.39 microm; for nebulizer B, MMAD = 1.1 microm.) For nebulizer A, percentage deposition in the treated and untreated lungs was not significantly different (50.8% versus 49.2%, respectively), while for nebulizer B, the median deposition in the carbachol treated lung was significantly greater than in the untreated lung (55.8% versus 44.2% respectively; p = 0.005). There was a more central pattern of deposition in the treated lung than in the untreated lung for both nebulizers, but the degree of central deposition was significantly greater with nebulizer B. The findings of the present study suggest that regional obstruction does not preclude the delivery of therapeutic aerosols to the airways in such a region, and may, depending on the size of the aerosol, result in enhanced airway deposition relative to less obstructed regions.

Behavioural and physiological responses of sheep to 16 h transport and a novel environment post-transport.

The effect of a novel lairage environment on the ability of sheep to recover from 16 h of transport was investigated. Sheep were transported from grass paddocks to either novel outside paddocks or inside pens, and housed groups were transported to either familiar or novel inside pens. During transport, sheep from outside paddocks lay down less than those from inside pens. In sheep transported to inside pens, those from outside paddocks spent more time lying and spent less time eating; hay and water intakes during the first 12 h post-transport were lower than those previously kept inside. There was no obvious effect of a novel environment post-transport on blood biochemistry, suggesting that the lower post-transport feed and water intakes in a novel environment did not have a significant effect on the ability of the sheep to recover from the feed and water deprivation associated with transport.

Inhaled antimicrobial therapy.

Although antimicrobial therapy has been administered through the inhaled route for decades, it has always been controversial. There are relatively few accepted indications for this mode of administration. Well-controlled studies of aerosolized antibiotics in cystic fibrosis demonstrate that tobramycin on a cyclical basis may reduce sputum volume, bacterial counts, and improve pulmonary function. Preliminary data indicate that inhaled antibiotic therapy of ventilator-associated tracheobronchitis may reduce sputum volume, but the clinical significance of this finding remains to be determined. Inhaled pentamidine is used for prophylaxis of Pneumocystis carinii in patients with human immunodeficiency virus infection who are intolerant of oral prophylactic agents. Ribavirin has been used for 30 years to treat respiratory syncytial virus. The role, if any, of inhaled antifungal therapy with amphotericin B remains undetermined.

Haemolytic uraemic syndrome with shigella.

A 49-year-old male developed bloody diarrhoea whilst on a visit to India. Sigmoidoscopy and rectal biopsy showed acute colitis. Shigella dysentery type I was isolated from stool culture. Cytotoxin production by the organism was demonstrated. The patient developed acute renal failure, thrombocytopaenia and microangiopathic haemolytic anaemia. He required mechanical ventilation, haemodialysis, blood transfusion and antibiotic therapy and achieved a complete recovery. This is an unusual case of haemolytic uraemic syndrome complicating shigellosis in an adult.

Risk factors in inflammatory bowel disease.

A patient with inflammatory bowel disease may have several risk factors, including host defence and familial and environmental factors. Host defence factors include neutrophil and complement abnormalities and increased intestinal permeability. This may explain why elemental diets are effective treatment in Crohn's disease. Food is a major factor affecting the intestinal tract, and the considerable change in dietary habits during this century may explain why Crohn's disease has become more common. There is a geographic difference in the distribution of the disease. This could be due to difference in fish consumption. Fish oil has been shown to be effective in an uncontrolled study in the treatment of ulcerative colitis. This needs to be confirmed by ongoing controlled studies. Very few data have been published on the dietary habits of different countries. There is a need for a uniform dietary assessment that can be applied in a multicentre study. These studies would involve much co-operation but would yield important clues in the aetiology of inflammatory bowel disease.