The main objective of the transition from paediatric to adult health care services is to ensure that all adolescents continue to receive coordinated care after reaching adulthood.1 Medical personnel understand that when children grow up, there are adulthood-related issues such as pregnancy or drug-related illnesses that many paediatricians are not equipped to deal with. Thus, transferring patient care to adult facilities is often an essential and unavoidable event in the medical journey for children.

There is now ample evidence that children who acquire a major physical illness at an early age, such as chronic kidney disease, are also at risk of cognitive developmental delays.2 Thus, while all youths eventually experience transition in health care, paediatricians are particularly concerned about youths with physical and/or cognitive disabilities. Medical care for these individuals is often more complex: they will generally also need long-term therapies and require extra attention due to the accompanying suboptimal cognitive maturity. In order for their health care to successfully transition to adult facilities, it is crucial that these vulnerable youths receive sufficient and appropriate preparation.

Although the literature suggests that many children with physical and cognitive disabilities suffer profound and prolonged morbidities due to ineffective health care transitioning, paediatric caregivers in Hong Kong face wide-ranging predicaments both within and outside the health care system. Problems include the lack of a comprehensive health care policy, scarcity of transition programmes, inadequate physician training, and inadequate education and preparation of patients and/or their family. In “A proposal on child health policy for Hong Kong” published by the Hong Kong Paediatric Society in August 2015,3 paediatric health care professionals expressed their desire to set up and implement a comprehensive, yet effective child health care policy to address the many health care challenges in Hong Kong. The professional panel pointed out that among all major concerns, there was ultimately a lack of coordinated and uninterrupted care for children with special care needs and medical complexities. In particular, the transition of care for such children was especially fragmented.

Transition preparations for children with special needs have been a public concern in many developed countries.4 The US Government has also identified the need to involve more physicians in transition planning as a public health objective in the Healthy People 2020 project.4 5

Efforts have been made to develop transition programmes, for example, with the establishment of transition clinics that are directed by transition coordinators in conjunction with adult-care physicians.6 During the past decade, more and more organisations have taken the initiative to set up ‘Family-Centered Medical Homes‘ in order to integrate care for children with special needs.4

In 2011, the Transitions Clinical Report Authoring Group, along with representatives from the American Academy of Pediatrics, the American Academy of Family Physicians and the American College of Physicians, issued a clinical report on the practice-based implementation of transition for youth.7 The report offered a framework for training not only for the medical team, but also for educators, assistants, and families of youths in medical homes. This year, the National Institute for Health and Care Excellence in England also published their guidelines on the transition of care for young people.8 They provide practical advice for caregivers attempting to improve young people’s engagement with services.

There are also some other transition tools available through the Internet that may be able to be adapted for use in education for the general public or even as a means to assess whether patients are ready for health care transitions.9 One such tool that could be particularly beneficial is the MyHealth Passport,10 as well as other tools listed in the Health Care Transition Resources.11 Since children with special needs are heterogeneous in nature, there is currently no universal tool although most tools can potentially be customised for each individual child and his/her family according to cultural background and underlying disabilities.

In 2007, approximately 10 900 adolescents with disabilities between the ages of 14 and 17 years took part in the Survey of Adult Transition and Health.12 The results showed that only 21.6% of adolescents had undergone successful transition to adult care. This finding reflects the dire fact that despite all the efforts made, the health care system in its current state still fails to support the majority of youths with special needs who are exiting paediatric care. There remains a great need for research and evaluation on the outcome of the transition of children with disabilities into adult facilities.

In the current issue, Pin et al13 reports on their local pilot data on the clinical transition of adolescents with developmental disabilities. Among the surveyed children and their families, approximately 60% considered the transfer process to be suboptimal. Although the study was confounded by many limitations and the findings are far from conclusive, it sheds light on the underlying causes of dissatisfaction and hurdles associated with youth transition in Hong Kong. Since a solid understanding of the underlying problems is important in finding a solution, we desperately need more local and relevant information on how to improve the effectiveness and success of health care transfer for children with special needs.

One of the six core goals of the care of children with special needs, as identified by the Maternal and Child Health Bureau, is to ensure that these individuals continue to receive the support necessary for transitioning to adulthood.14 The ultimate goal is not just to provide the necessary medical care during transition, but also to enable individuals to succeed in all aspects of life so that they are able to work, to assimilate into society, and to achieve independence.

Now that the deficiencies have been identified, it is time for medical professionals to take the initiative and work together to help shape the future of health care for children with special needs.

1. Davis AM, Brown RF, Taylor JL, Epstein RA, McPheeters ML. Transition care for children with special health care needs. Pediatrics 2014;134:900-8. Crossref

2. Johnson RJ, Warady BA. Long-term neurocognitive outcomes of patients with end-stage renal disease during infancy. Pediatr Nephrol 2013;28:1283-91. Crossref

3. The Hong Kong Paediatric Society, The Hong Kong Paediatric Foundation, and Child Healthcare Professionals in Hong Kong. A proposal on child health policy for Hong Kong. 2015. Available from: http://hkpf.org.hk/download/20150920 Child Health Policy for Hong Kong_Final.pdf. Accessed Aug 2016.

4. McManus MA, Pollack LR, Cooley WC, et al, Current status of transition preparation among youth with special needs in the United States. Pediatrics 2013;131:1090-7. Crossref

5. Office of Disease Prevention and Health Promotion. 2020 Topics & Objectives: Disability and Health. Available from: https://www.healthypeople.gov/2020/topics-objectives/topic/disability-and-health/objectives. Accessed Aug 2016.

6. McQuillan RF, Toulany A, Kaufman M, Schiff JR. Benefits of a transfer clinic in adolescent and young adult kidney transplant patients. Can J Kidney Health Dis 2015;2:45. Crossref

7. American Academy of Pediatrics; American Academy of Family Physicians; American College of Physicians; Transitions Clinical Report Authoring Group, Cooley WC, Sagerman PJ. Supporting the health care transition from adolescence to adulthood in the medical home. Pediatrics 2011;128:182-200. Crossref

8. NICE Pathway—Transition from children’s to adults’ services for young people using health or social care services. NICE Guideline 43. 24 February 2016. Available from: https://www.nice.org.uk/guidance/NG43. Accessed Aug 2016.

9. Schwartz LA, Daniel LC, Brumley LD, Barakat LP, Wesley KM, Tuchman LK. Measures of readiness to transition to adult health care for youth with chronic physical health conditions: a systematic review and recommendations for measurement testing and development. J Pediatr Psychol 2014;39:588-601. Crossref

10. The Hospital for Sick Children, Good 2 Go Transition Program—MyHealth Passport. Available from: https://www.sickkids.ca/myhealthpassport/. Accessed Aug 2016.

11. Got Transition. Health care transition resources. Available from: http://www.gottransition.org/resources/. Accessed Aug 2016.

12. Oswald DP, Gilles DL, Cannady MS, Wenzel DB, Willis JH, Bodurtha JN. Youth with special health care needs: transition to adult health care services. Matern Child Health J 2013;17:1744-52. Crossref

13. Pin TW, Chan WL, Chan CL, et al. Clinical transition for adolescents with developmental disabilities in Hong Kong: a pilot study. Hong Kong Med J 2016;22:445-53. Crossref

14. US Department of Health and Human Services. The National Survey of Children with Special Health Care Needs Chartbook 2005-2006. Rockville: Department of Health and Human Services; 2008.

Breast cancer poses a significant health burden worldwide. It is the most common cancer in women with nearly 1.7 million new cases diagnosed globally in 2012.1 Early detection reduces mortality and mammogram screening has been shown to achieve a mortality reduction of 25% to 28%.2 3 Many countries have a breast screening programme, including the UK, Australia, Norway, Sweden, the US, Singapore, Japan, and Korea. Population screening for breast cancer remains controversial, however, especially the decision on whom, when, and how to screen due to different epidemiological characteristics of breast cancer in different populations. In Hong Kong, the incidence and mortality of Asian female breast cancer is lower compared with the Caucasian population. In the Surveillance and Health Services Research in 2013, the American Cancer Society published a lifetime risk of 1 in 8 for developing invasive female breast cancer,4 similar to the findings of Cancer Research UK in 2010.5 The median age at diagnosis of cancer was 61 years in 2006 to 2010 in these studies. In Hong Kong, breast cancer is the number-one female cancer with 3524 cases of invasive cancer diagnosed in 2013. The lifetime risk of female breast cancer before the age of 75 years was 1 in 17. Breast cancer in Hong Kong occurs at a younger age compared with the western population. The median age at diagnosis of breast cancer was 54 years.6 Due to different tumour characteristics and the overall smaller size and denser fibroglandular tissue of Asian women’s breasts, local epidemiology and clinical studies are important to facilitate our understanding of this common disease in Hong Kong. In this issue of the Hong Kong Medical Journal, studies conducted by Lau et al7 and Chan et al8 in Hong Kong provide valuable local data on this important topic.

Lau et al7 compared the surgical outcome and pathology of breast cancer in self-detected and screen-detected women (physical breast examination, mammogram, or ultrasound) in their institute in Hong Kong. Several interesting aspects are raised. First, the screen-detected group had a smaller tumour of an earlier stage and lower grade with less lymph node involvement. This could imply that early detection may result in better prognosis. Previous studies have suggested reduced mortality with early breast cancer detection.9 Less-invasive surgery is feasible such as breast-conserving surgery with better cosmetic outcome. Second, there was a trend towards increased detection of smaller tumours of <2 cm in the screen-detected group, likely explained by the advances in radiological imaging technology in mammogram and ultrasound. The self-detection trend remained static suggesting no significant change in skills throughout the study period. While the difference did not reach statistical significance, the trend could suggest a higher sensitivity of radiological imaging to detect small tumours. Third, the mean age at first diagnosis of breast cancer was 50 years (range, 24-92 years) and median age of 40 to 49 years in both the self-detected and screen-detected groups in this study. This is substantially lower than the median age of 54 years reported in the Hong Kong Cancer statistics in 20136 and the age of 61 years reported for the UK and the US in 2010.4 5 Notably, the highest proportion of breast cancer was detected in the 40- to 49-year-old age-group in this study (38.6% and 43.5% of the self-detected and screen-detected group, respectively). A striking proportion of breast cancer was also detected in the 20- to 39-year-old age-group (16.6% and 7.0% in the self-detected and screen-detected group, respectively). This finding of breast cancer at younger age deserves further research and attention.

Chan et al8 explored the impact of a radiolucent MammoPad (Hologic Inc, Bedford [MA], US) during mammogram on pain/comfort level, radiation dose, and image quality. Mammography involves breast compression in two or more views with radiation exposure. Discomfort and pain are often encountered during breast compression and may affect a woman’s willingness to undergo a mammogram. In their study, most women (71%) experienced less pain, coldness, and hardness of the paddle with a better overall feeling. None of the patients reported additional discomfort with the pad. Women with less-dense breasts were more likely to experience more comfort with the pad. Age and breast size did not relate to the degree of discomfort during mammogram. Comparable image quality between the padded and non-padded side was noted in 92% of women. While image quality difference was perceived in 4%, none was considered to have affected the diagnostic accuracy. Furthermore, glandular dose was 6.5% less in the mediolateral oblique view and 4.5% less in the craniocaudal view when a pad was used. Nonetheless, the role and efficacy of the MammoPad in diagnostic mammography was not determined in this study due to the exclusion of women with known carcinoma, scarring, or pathology detected by clinical breast examination. Further, the additional time required and cost of applying a single-use MammoPad may raise financial concerns in the setting of a publicly funded large-scale breast screening programme, unless the cost can be further lowered or pads can be recycled following effective sterilisation.

Despite agreement on the benefit of early cancer detection and treatment, debate about population-based breast cancer screening remains. The younger age of disease onset identified by Lau et al7 deserves further attention as high breast density, associated with younger age and lower body mass index, reduces mammogram sensitivity. Newer technology such as digital breast tomosynthesis may provide higher sensitivity and increase cancer detection rate compared with digital mammography because of its ability to remove overlapping glandular tissue, the main reason for both false-positive and -negative results with traditional mammography.10 11 12 13 14 Although tomosynthesis requires breast compression similar to mammogram, the compression force may be lower without affecting image quality.14 Further studies would be helpful to determine whether the benefits of the MammoPad used by Chan et al8 could have further benefit in tomosynthesis.

Hong Kong currently has no government-subsidised programme for breast cancer screening. Self-financed opportunistic screening is available mostly in the private sector. The suitability of breast cancer screening on a population-wide level in Hong Kong, including cost-effectiveness,15 remains to be determined. Such a decision should be evidence-based and tailored to local epidemiology so that the benefits of screening outweigh the risks. In addition, the method of screening should be sensitive and suitable for the woman’s breast density, age, and personal and family risk of developing breast cancer.

1. Ferlay J, Soerjomataram I, Ervik M, et al. GLOBOCAN 2012 v1.1, Cancer Incidence and Mortality Worldwide: IARC CancerBase No. 11. Lyon, France: International Agency for Research on Cancer; 2014. Available from: http://www.wcrf.org/int/cancer-facts-figures/data-specific-cancers/breast-cancer-statistics. Accessed 16 Jan 2015.

2. Weedon-Fekjær H, Romundstad PR, Vatten LJ. Modern mammography screening and breast cancer mortality: population study. BMJ 2014;348:g3701. Crossref

3. World Health Organization. IARC handbooks of cancer prevention: handbook 7: breast cancer screening. IARC Press; 2001.

4. American Cancer Society. Breast Cancer Facts & Figures 2013-2014. Atlanta: American Cancer Society Inc; 2013.

5. Lifetime risk estimates calculated by the Statistical Information Team at Cancer Research UK. Based on data provided by the Office of National Statistics, ISD Scotland, the Welsh Cancer Intelligence and Surveillance Unit and the Northern Ireland Cancer Registry, on request, December 2013 to July 2014. Available from: http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/breast-cancer/incidence-invasive#heading-Four. Accessed Apr 2016.

6. Female breast cancer in 2013. Hong Kong Cancer Registry, Hospital Authority, February 2016. Available from: http://www3.ha.org.hk/cancereg/breast_2013.pdf. Accessed Apr 2016.

7. Lau SS, Cheung PS, Wong TT, Ma MK, Kwan WH. Comparison of clinical and pathological characteristics between screen-detected and self-detected breast cancers: a Hong Kong study. Hong Kong Med J 2016;22:202-9. Crossref

8. Chan HH, Lo G, Cheung PS. Is pain from mammography reduced by the use of radiolucent MammoPad? Local experience in Hong Kong. Hong Kong Med J 2016;22:210-5. Crossref

9. Gøtzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database Syst Rev 2011;(1):CD001877. Crossref

10. Lei J, Yang P, Zhang L, Wang Y, Yang K. Diagnostic accuracy of digital breast tomosynthesis versus digital mammography for benign and malignant lesions in breasts: a meta-analysis. Eur Radiol 2014;24:595-602. Crossref

11. Friedewald SM, Rafferty EA, Rose SL, et al. Breast cancer screening using tomosynthesis in combination with digital mammography. JAMA 2014;311:2499-507. Crossref

12. Ciatto S, Houssami N, Bernardi D, et al. Integration of 3D digital mammography with tomosynthesis for population breast-cancer screening (STORM): a prospective comparison study. Lancet Oncol 2013;14:583-9. Crossref

13. Skaane P, Bandos Al, Gullien R, et al. Comparison of digital mammography alone and digital mammography plus tomosynthesis in a population-based screening program. Radiology 2013;267:47-56. Crossref

14. Förnvik D, Andersson I, Svahn T, Timberg P, Zackrisson S, Tingberg A. The effect of reduced breast compression in breast tomosynthesis: human observer study using clinical cases. Radiat Prot Dosimetry 2010;139:118-23. Crossref

15. Wong IO, Kuntz KM, Cowling BJ, Lam CL, Leung GM. Cost-effectiveness analysis of mammography screening in Hong Kong Chinese using state-transition Markov modelling. Hong Kong Med J 2010;16 Suppl 3:38S-41S.

The global increasing elderly population is placing a great burden on the financial and health systems of all countries. A major source of this burden is fragility fracture.1 In Hong Kong, around 6000 patients present each year with hip fracture, and current projections indicate that the numbers will double by 2050.2 3

Fragility fracture has long been a major source of the workload for orthopaedic departments in Hong Kong. Patients with hip, vertebral, or wrist fracture occupy a high percentage of orthopaedic beds in all public hospitals. Most hip fractures require either internal fixation or hip replacement to alleviate fracture pain and allow early ambulation.4 5 A decade ago, most hip fracture patients in Hong Kong would wait 5 to 6 days for surgery because health personnel—including orthopaedic surgeons, anaesthetists, and nurses—did not consider the condition to be important. Nonetheless such a delay is now known to increase in-patient and postoperative mortality and morbidity. The Blue Book of the British Orthopaedic Association 2007 stated that hip fractures should be operated on within 48 hours.2 In 2009, the Hospital Authority selected geriatric hip fracture as the first Key Performance Indicator for orthopaedics in Hong Kong.6 The aim was to confine preoperative stay to no more than 2 days for 70% of hip fracture patients. Prior to 2007 this figure was approximately 30%, but had improved to 62% by August 2008. The mean preoperative length of stay has now been reduced by 3.5 days, from the previous 6 days. By 2009, the hard work of all orthopaedic surgeons, geriatricians, and allied health colleagues had shortened the waiting time to 2 days in 70% of patients.6 Postoperative mortality and morbidity are also much reduced and, more importantly, the length of time the patient has fracture pain. These elderly now walk earlier and are discharged earlier. Thus their quality of life is improved and more hospital beds are available for other patients.

There are a few tests that help the orthopaedic surgeons to assess mortality risks of hip fracture patients. They are discussed in one of the articles in this issue, and improve communication between the doctor and patient’s family, as well as minimising any misunderstanding.7

In patients with vertebral fracture, treatment is mostly conservative although some suffer significant back pain and may be bedridden for a few months. Nonetheless with advances in technology patients who do not respond well to conservative treatment now benefit from vertebroplasty, which implies injection of bone cement into the fractured vertebra.8 Good pain relief is achieved in many patients postoperatively, enabling early rehabilitation.

Wrist fracture is a very common problem in the elderly after a fall. For a long time, treatment was focused on closed reduction and application of plaster-of-Paris (POP) although such plaster immobilisation resulted in stiffness and pressure sores. Patients often required a long period of physiotherapy to regain movement. Internal fixation was seldom performed because the failure rate with old implants was high. The development of new locking anatomical plates and bone substitute has greatly improved the success rate of surgery and these patients can now move their wrist much earlier following surgery and avoid the complications associated with POP immobilisation.

With increasing use of new surgical techniques and implants, the number of operative complications is expected to rise. The price of the implants is also considerably increased and management of complications is often difficult in these elderly patients. This may place increasing demands on hospital services and budget. Adequate training and supervision of junior doctors is required to ensure the job is done well.

Prevention is always better than treatment. Several osteoporotic drugs are widely used to help in the treatment and prevention of osteoporosis. Their use is usually long-term and they are not cheap, however.

Apart from osteoporosis, sarcopenia is another factor that causes fall of the elderly and is also discussed in this issue of the journal.9 Paying more attention to nutrition is very important in these elderly to build up muscle bulk. Many of these patients have medical co-morbidities so collaboration of geriatricians with orthopaedic surgeons is of utmost importance to ensure uninterrupted and well-coordinated pre- and post-operative care. All patients with fragility fracture after a fall should be offered a multidisciplinary service to prevent another fall. It is advisable for public hospitals to organise a team of staff that includes orthopaedic surgeons, geriatricians, allied health colleagues and nurses with special interest in this field to manage these patients with fragility fracture together.

Longevity is nothing to admire, rather we should pursue a better quality of life for our senior citizens. Looking after patients with fragility fracture well is a lot cheaper than looking after them badly. The Hong Kong SAR Government and community should invest more in the care of these patients. The rewards can be surprisingly high.

1. American Academy of Orthopaedic Surgeons. Position statement: Recommendations for enhancing the care of patients with fragility fractures. June 2003. Revised December 2009. Available from: http://www.aaos.org/CustomTemplates/Content.aspx?id=22324&ssopc=1. Accessed Dec 2015.

2. The care of patients with fragility fracture. British Orthopaedic Association. September 2007. Available from: http://www.fractures.com/pdf/BOA-BGS-Blue-Book.pdf. Accessed Dec 2015.

3. Man LP, Ho AW, Wong SH. Excess mortality for operated geriatric hip fracture in Hong Kong. Hong Kong Med J 2016;22:6-10. Crossref

4. Hip fracture: management. Clinical guideline. National Institute for Health and Care Excellence (NICE). 22 June 2011. Available from: http://www.nice.org.uk/guidance/cg124/resources/hip-fracture-management-35109449902789. Accessed Dec 2015.

5. Chan VW, Chan PK, Chiu KY, Yan CH, Ng FY. Why do Hong Kong patients need total hip arthroplasty? An analysis of 512 hips from 1998 to 2010. Hong Kong Med J 2016;22:11-5. Crossref

6. Report of the Chairman. COC in Orthopaedics and Traumatology. Hong Kong: Hospital Authority; 2009.

7. Lau TW, Fang C, Leung F. Assessment of postoperative short-term and long-term mortality risk in Chinese geriatric patients for hip fracture using the Charlson comorbidity score. Hong Kong Med J 2016;22:16-22. Crossref

8. Heini PF, Wälchli B, Berlemann U. Percutaneous transpedicular vertebroplasty with PMMA: operative technique and early results. A prospective study for the treatment of osteoporotic compression fractures. Eur Spine J 2000;9:445-50. Crossref

9. Ho AW, Lee MM, Chan EW, et al. Prevalence of pre-sarcopenia and sarcopenia in Hong Kong Chinese geriatric patients with hip fracture and its correlation with different factors. Hong Kong Med J 2016;22:23-9. Crossref

Since 2010, paracetamol has been the most common agent used in Hong Kong for deliberate self-harm by overdose and poisoning.1 It is readily available over-the-counter and is commonly prescribed by doctors. There are more than 900 registered pharmaceuticals that contain paracetamol in Hong Kong. Paracetamol overdose can result in delayed, sometimes life-threatening, liver injury and dose-dependent damage. N-acetylcysteine (NAC) is well known to be an effective antidote that can prevent liver injury if administered in time. The decision to give NAC can be facilitated by plotting the serum paracetamol concentration against time since ingestion on the Rumack-Matthew nomogram.2 Serum concentration above the treatment line on the nomogram indicates the need for NAC therapy.

There are three treatment lines on the Rumack-Matthew nomogram: 100-treatment line, 150-treatment line, and 200-treatment line. Currently, the 150-treatment line is commonly used in most parts of the world including the US, Australia, and New Zealand. The 150-treatment line is parallel to the original 200-treatment line but has been arbitrarily lowered by 25% to improve sensitivity. The Hong Kong Poison Information Centre also recommends the 150-treatment line and most clinicians in Hong Kong follow this recommendation. In the UK, the original 200-treatment line was used for normal-risk patients and the 100-treatment line reserved for high-risk patients. Over the years, cases of liver failure accumulated when patients were treated according to the 200-treatment line. Thus in 2012 the health department in the UK decided to abandon the two-level approach and apply one treatment line of 100 mg/L for all patients.3

In the article written by Chan et al,4 the 150-treatment line has been evaluated and identified a failure rate of 0.45%. All four index patients developed chemical hepatitis that responded to supportive treatment. The incidence of 150-treatment line failures in the US has been reported as 1% to 3% and thought to be predominantly due to inaccurate ingestion history.5 Looking closely at the four cases presented in Chan et al’s study,4 two of them presented late, and in most cases there was an apparent discrepancy between the dose taken and the achieved paracetamol level. Similar to the US experience, an inaccurate ingestion history might explain treatment-line failure for some of these cases. Further evidence from more robust studies is needed before a recommendation can be made to lower the treatment threshold to the UK standard.

Obtaining an accurate history from patients who deliberately self-harm is known to be difficult. Patients may be unwilling or unable to provide accurate information to the clinician. According to the author’s own experience in managing such patients, history taking must be done tactfully and sometimes repeatedly from different sources of information. An astute physician should make the decision to give NAC after analysing all the available evidence including the best-gathered history, the clinical presentation, and the remaining treatment-time window, together with the serum paracetamol level. Laboratory tests may help but can never replace clinical skill, clinical judgement, and experience in patient management.

Previously, the responsibility for managing such time-critical overdosed patients was often borne by interns and junior residents. The quality of care provided may not have been optimal. Over the past 10 years emergency physicians and trainees have received intensive training in the management of toxicology cases based on updated evidence and standards. In addition, groups of interested emergency physicians have formed toxicology teams to oversee and support the management of poisoning patients in individual hospitals. This model of care improves patient outcome and shortens the length of stay for medical treatment.6 7 Such improvements might explain the observed good outcome for Chan et al’s cohort4 of patients with paracetamol overdose.

1. Chan YC, Tse ML, Lau FL. Hong Kong Poison Information Centre: Annual Report 2013. Hong Kong J Emerg Med 2014;21:249-59.

2. Rumack BH, Matthew H. Acetaminophen poisoning and toxicity. Pediatrics 1975;55:871-6.

3. Paracetamol overdose: new guidance on use of intravenous acetylcysteine. Commission of Human Medicine, United Kingdom. Available from: http://www.mhra.gov.uk/home/groups/pl-p/documents/drugsafetymessage/con178654.pdf. Accessed Aug 2015.

4. Chan ST, Chan CK, Tse ML. Paracetamol overdose in Hong Kong: is the 150-treatment line good enough to cover patients with paracetamol-induced liver injury? Hong Kong Med J 2015;21:389-93. Crossref

5. Rumack BH. Acetaminophen hepatotoxicity: the first 35 years. J Toxicol Clin Toxicol 2002;40:3-20. Crossref

6. Chung AH, Tsui SH, Tong HK. The impact of an emergency department toxicology team in the management of acute intoxication. Hong Kong J Emerg Med 2007;14:134-43.

7. Ko S, Chan HY, Ng F. The impact of Emergency Medicine Ward in acute intoxication management. Hong Kong J Emerg Med 2010;17:323-31.

Preimplantation genetic diagnosis (PGD) gives couples who are at risk of having a child with an inherited genetic disorder or chromosome abnormality, a chance to have an unaffected child without undergoing termination or miscarriage of an affected pregnancy. Embryos obtained from in-vitro fertilisation (IVF) with or without intracytoplasmic sperm injection are tested genetically prior to selective transfer of unaffected ones into the uterus. The physical and psychological complications of a termination or miscarriage, especially in repeated situations, should not be underestimated.

In PGD, DNA can be obtained by blastomere biopsy at the cleavage stage, trophectoderm cell biopsy when an embryo has developed to the blastocyst stage or biopsy of one or both polar bodies. Compared with cleavage stage biopsy, trophectoderm biopsy does not adversely impact the embryo, although vitrification and cryopreservation of the embryo may be required to allow time for genetic analysis.1 Although polar body biopsy is less invasive, it is less predictive of actual clinical outcome than direct embryo assessment.2

Genetic laboratories have developed their own protocols to perform different molecular tests on the limited amount of DNA obtained from biopsy. Traditionally, fluorescent in-situ hybridisation is used for cytogenetic diagnosis, and polymerase chain reaction for molecular diagnosis. New technologies, including array comparative genomic hybridisation (CGH) and single nucleotide polymorphism (SNP) microarrays, can improve diagnostic accuracy.3 4 The single-cell whole genome amplification (WGA) method allows subsequent mutation study, directly by minisequencing and/or indirectly by linkage analysis alongside the mutation test. It also allows simultaneous PGD for more than one indication.5

The indications for PGD are increasing. Common ones include single-gene disorders, X-linked diseases, and inherited chromosome abnormalities. Preimplantation genetic diagnosis of predisposition to inherited cancer such as breast cancer (BRCA mutation) is also emerging.6 Nonetheless, social sexing is prohibited in Hong Kong and Europe. Legislation and regulation of PGD also vary among different countries.

Aneuploidy is the most common cause of repeated implantation failure and recurrent miscarriage. As such, preimplantation genetic screening (PGS), using similar technology to PGD, is offered to improve delivery rates in patients of advanced maternal age, and in those with repeated implantation failure, repeated miscarriages, and severe male factor infertility. Evidence that PGS can help improve delivery rates is conflicting, however.7 Whether PGS using array CGH or SNP microarrays can increase delivery rates requires further study.

In 2006, a tertiary centre in London reported their experience of 330 PGD cycles including 96 cycles for single-gene disorders and 62 cycles for X-linked disorders.8 In 62% of the cycles, there was at least one unaffected embryo available for transfer, resulting in 90 pregnancies, 68 clinical pregnancies, and 58 live births. The clinical pregnancy rate and live birth rate was 33% and 28% per cycle started, respectively.8 This result was similar to a clinical pregnancy rate of 30.2% per transfer reported by the European Society of Human Reproduction and Embryology PGD Consortium in 2014.9

In this issue, authors in a local tertiary centre reported their 6-year experience of 124 PGD cycles for monogenetic diseases in 76 couples using WGA and linkage analysis.10 The ongoing pregnancy rate was 28.2% per initiated cycle and 38.0% per fresh embryo transfer.10 These pregnancy rates were similar to those of PGD using frozen-thawed embryo transfer cycles and for IVF for routine infertility treatment. Approximately 19% of the cycles for PGD were cancelled after initiation of stimulation. Approximately 70% of PGD was performed for thalassaemia (α or β), and the remaining 30% for 19 other monogenetic diseases that included spinocerebellar ataxia type 3 and Huntington’s disease. No misdiagnosis was found in this small series according to the available data.10

In clinical practice, thalassaemia is the most common single-gene disorder in Hong Kong. When both parents are a β-thalassaemia carrier, there is a 25% risk of having a fetus affected by homozygous β-thalassaemia. Conventional prenatal diagnosis is an option but couples will face termination of pregnancy if an affected pregnancy is detected. For an unaffected pregnancy, human leukocyte antigen (HLA) typing can subsequently be performed but may not be compatible with a previously affected child. On the other hand, PGD allows at-risk couples the chance to have an unaffected child without undergoing termination or miscarriage of an affected pregnancy. In addition, PGD can be offered to at-risk couples even in the absence of a previously affected pregnancy. It can also allow selection of an unaffected and HLA-compatible embryo simultaneously before transfer into the uterus. This results in subsequent availability of HLA-matched cord blood at birth for transplant to an affected elder sibling.

In a local study of women at risk,11 in particular those with subfertility problems or with a child affected by major thalassaemia, PGD provided an acceptable alternative to conventional prenatal diagnosis. Couples also had a positive attitude to the use of PGD/HLA typing to reproduce a ‘saviour child’ to save an affected sibling.12 It is unknown, however, whether Hong Kong women at risk of other genetic disorders share this view.

Preimplantation genetic diagnosis requires close collaboration between different specialists including obstetricians, fertility specialists, IVF laboratory, and human geneticists. It needs intensive effort and expensive techniques, and is demanding for the patients. In Hong Kong, the high costs of PGD and IVF must be borne by the patient. It is important to inform patients about the success rate and potential risks of IVF and PGD, possible complications of ovarian hyperstimulation, and the risk of multiple pregnancy.

Because of the possibility of mosaicism related to blastomere or trophectoderm cell biopsy and the false-negative rate due to allelic dropout or contamination related to the limited amount of DNA obtained from PGD, prenatal diagnosis is still recommended after PGD. Prenatal diagnosis is made following an invasive test such as chorionic villus sampling or amniocentesis or, in suitable situations, by a non-invasive approach such as testing of cell-free fetal DNA in maternal plasma for chromosomal abnormalities or by serial ultrasound examinations to exclude haemoglobin Bart’s disease.

There are ethical concerns that arise with new technologies such as microarrays and WGA that generate more detailed and complex genetic information than previous conventional approaches, and make preconception carrier testing feasible.13 Genetic laboratories should report their results according to internationally accepted accreditation standards.14 Adequate pre-testing counselling is important.

With a multidisciplinary approach and advances in technology, PGD is a great opportunity for couples at risk. It allows them to have an unaffected child while avoiding the need to terminate an affected pregnancy, and makes HLA-matched cord blood available at birth for transplantation to a previously affected child. Nonetheless, the process is expensive, demanding for couples, not always successful, and not without risks. Couples at risk should be well informed about the two reproductive options, namely PGD and prenatal diagnosis, in pre-pregnancy counselling.

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