Safe Staffing and Nurse-to-Patient Ratios Around the World: The Complete Guide

How many patients can one nurse safely care for? It is one of the most important questions in healthcare, and one of the most contested. Large international studies have found that each additional patient added to a hospital nurse’s workload is associated with a measurable increase in the risk of patients dying, alongside more complications, longer stays and more missed care. Yet nurses in many countries routinely care for far more patients than the evidence suggests is safe, especially on night shifts and in under-resourced settings.

Safe staffing is about more than numbers. It depends on how sick patients are, the skills and experience of the team, the layout of the ward, the support available, and the unpredictable events of every shift. This complete guide explains the evidence linking nurse staffing to outcomes, the main approaches to setting staffing levels, how ratio laws work in different parts of the world, what “missed care” means, the arguments for and against mandated ratios, and what nurses can do when staffing is unsafe.

What is safe staffing?

Safe staffing means having the right number of nurses, with the right skills and experience, in the right place, at the right time, to meet patients’ needs safely and effectively. It includes:

• Numbers: enough nurses for the number of patients.
• Skill mix: the right balance of registered nurses, specialist nurses, nursing assistants and other staff.
• Experience: a mix of experienced and newer nurses, with support for those still developing.
• Patient acuity and dependency: how unwell patients are and how much care they need.
• Environment: ward layout, single rooms, availability of equipment and support services.
• Flexibility: the ability to respond when demand changes during a shift.

Nurse-to-patient ratios are one tool for describing and setting staffing levels, but safe staffing is a broader concept.

The evidence: why staffing matters

Research over the past two decades provides strong evidence that nurse staffing affects patient outcomes:

• Mortality: a landmark study in Pennsylvania hospitals published in 2002 found that each additional patient per nurse was associated with around a 7 percent increase in the odds of a surgical patient dying within 30 days. Subsequent large studies in Europe, including the RN4CAST study across many countries, found similar associations, along with lower mortality where a higher proportion of nurses held bachelor’s degrees.
• Failure to rescue: lower staffing is linked to higher rates of patients dying after complications that could have been recognised and treated.
• Adverse events: low staffing is associated with more falls, pressure injuries, healthcare-associated infections, medication errors and readmissions.
• Length of stay: better staffing is linked with shorter hospital stays.
• Patient experience: patients report better care where staffing is adequate.
• Nurse outcomes: poor staffing is associated with burnout, job dissatisfaction, intention to leave and sickness absence.

The quality of the work environment also matters: studies suggest that improving staffing has the greatest benefit in hospitals with good working environments, where nurses are supported and involved in decisions.

Research on skill mix has found that replacing registered nurses with less qualified staff is associated with worse patient outcomes, even when total staff numbers stay the same. Nursing assistants are vital members of the team, but they cannot substitute for registered nurses’ assessment and clinical judgement.

Missed care

When staffing is inadequate, nurses are forced to prioritise, and some care is left undone. This is known as missed care, care left undone or implicit rationing. Studies across many countries consistently find that the most commonly missed activities include:

• Comforting and talking with patients.
• Patient education and discharge planning.
• Mouth care and skin care.
• Turning and repositioning.
• Mobilising patients.
• Timely observations and monitoring.
• Timely medicines and pain relief.
• Updating care plans and documentation.

Missed care is linked to poorer outcomes, including higher mortality, and to nurses’ moral distress. It is often invisible to managers and policymakers because it does not show up in standard activity data.

How staffing levels are set

There are several main approaches to deciding how many nurses a ward or unit needs. Most systems use a combination.

Mandated minimum ratios

Fixed minimum nurse-to-patient ratios set in law or regulation, for example one registered nurse to every four or five patients on a medical-surgical ward during the day. Ratios are simple to understand, easy to monitor and enforceable, but they may not reflect differences in patient acuity, and there is a concern that minimums can become maximums.

Nurse hours per patient day

Some systems set a required number of nursing hours per patient per day, allowing flexibility in how shifts are staffed, but which can be harder for frontline nurses to monitor.

Acuity and dependency tools

Patient classification or acuity tools measure how much nursing care each patient needs, for example based on their level of dependency, observations required, and treatments. The results are used to calculate the number of nurses needed. Examples include tools developed in national health systems, which often combine acuity data with professional judgement. These approaches are more responsive to patient needs but depend on accurate, consistent use and on organisations acting on the results.

Professional judgement

Experienced nurses assess the needs of their patients and environment to decide on staffing. Professional judgement is essential but can be influenced by budget pressures and normalisation of understaffing if used alone.

Staffing committees and frameworks

Some jurisdictions require hospitals to have staffing committees, often with frontline nurse representation, to develop and review staffing plans, with public reporting.

Benchmarking

Comparing staffing with similar wards or hospitals. This can be useful but risks reinforcing poor standards if comparison units are themselves understaffed.

Ratio laws and staffing policies around the world

Countries and regions have adopted different approaches. Details change over time, so nurses should check current legislation and policies in their own jurisdiction.

California, United States

California became the first US state to implement comprehensive minimum nurse-to-patient ratios in hospitals, with the law taking full effect in the mid-2000s. Ratios vary by unit, such as one nurse to two patients in intensive care and one nurse to five patients on medical-surgical units, and apply at all times, including breaks. Research comparing California with other states found that California nurses cared for fewer patients on average and that lower workloads were associated with lower mortality and lower burnout. Other US states have introduced staffing committees, disclosure requirements or ratios in specific settings, and Oregon passed hospital ratio legislation in 2023. Debate continues at federal level.

Victoria and Queensland, Australia

Victoria introduced nurse-to-patient ratios through industrial agreements in 2000 and later enshrined them in legislation, the first Australian state to do so. Queensland introduced legislated minimum ratios for public medical and surgical wards in 2016, set at one nurse to four patients on morning and afternoon shifts and one nurse to seven on night shifts. A large evaluation published in The Lancet found that after the law was introduced, patients in hospitals with ratios had lower odds of dying and of readmission, shorter stays, and that the costs of extra nurses were substantially offset by savings from fewer readmissions and shorter stays. Other Australian states have since adopted or committed to ratios.

Wales and Scotland, United Kingdom

Wales became the first UK nation to pass a safe nurse staffing law, the Nurse Staffing Levels (Wales) Act 2016, which requires health boards to calculate and maintain nurse staffing levels on specified wards using a set method combining acuity tools, professional judgement and quality indicators, and to report on compliance. Scotland passed the Health and Care (Staffing) (Scotland) Act 2019, which places duties on health and care services to ensure appropriate staffing using common methods, and came into force in 2024. These laws do not set fixed ratios, but create a legal duty and a structured method. England relies on guidance and does not have a staffing law.

Canada

Staffing policy is a provincial responsibility. In 2023, British Columbia announced plans for minimum nurse-to-patient ratios in hospitals, the first province to do so, and nursing unions in other provinces have campaigned for similar measures.

Ireland

Ireland developed a national Framework for Safe Nurse Staffing and Skill Mix, initially for medical and surgical wards in acute hospitals and later for emergency departments, using a systematic approach based on patient needs and evidence. Evaluations showed improved outcomes in pilot hospitals.

Asia

Several Asian countries have staffing standards linked to hospital accreditation or payment systems. Japan, for example, links hospital reimbursement to nurse staffing levels, with higher payment for wards meeting richer staffing standards, such as one nurse to seven patients. South Korea has used payment incentives and pilot programmes to improve staffing in comprehensive nursing care wards. Other countries specify staffing standards in regulations or accreditation, but enforcement varies.

Low- and middle-income countries

Many low- and middle-income countries have national staffing norms or standards in policy documents, but severe shortages, budget constraints and limited enforcement mean that actual staffing often falls far below them. Ratios of one nurse to 20, 30 or more patients on night shifts are reported in some settings. Addressing staffing in these contexts requires investment in education, employment and retention, alongside realistic standards and accountability.

Recommended ratios and benchmarks

There is no single global standard, because safe staffing depends on context. However, evidence and existing laws provide useful reference points. On general medical and surgical wards, research from multiple countries suggests that caring for more than about six to eight patients per registered nurse is associated with significantly worse outcomes, and many ratio laws set daytime minimums around one nurse to four or five patients. Intensive care units typically aim for one nurse to one or two patients, depending on acuity. Emergency departments, maternity, paediatrics, mental health and long-term care each require specific standards. Professional nursing organisations in many countries have published recommendations for their specialties.

The case for mandated ratios

• Evidence: studies of ratio laws in California and Queensland show benefits for patients and nurses.
• Clarity: ratios are simple for nurses, managers and the public to understand.
• Enforceability: clear minimums can be monitored and enforced.
• Retention: manageable workloads help keep nurses in the profession and can attract former nurses back.
• Protection against cost-cutting: ratios prevent staffing being reduced to save money.
• Cost-effectiveness: savings from fewer complications and shorter stays can offset much of the cost.

The case against, or for alternative approaches

• Inflexibility: fixed ratios may not reflect differences in patient acuity, and minimums may become the norm.
• Supply: in countries with severe shortages, there may not be enough nurses to meet ratios, potentially forcing closures of beds or services.
• Cost: ratios require upfront investment, which governments and hospitals may resist.
• Skill mix: some argue ratios could reduce the use of nursing assistants or other team members.
• Alternatives: some jurisdictions prefer legal duties combined with acuity-based methods, as in Wales and Scotland.

Many experts conclude that the best approach combines enforceable minimum standards with acuity-based tools, professional judgement, transparent reporting, and investment in the workforce needed to meet them.

Measuring acuity and workload

Acuity tools help capture the reality of nursing workload. They typically categorise patients by the level of care needed, such as stable patients requiring standard care, patients needing frequent observations or assistance, and highly dependent or unstable patients. Workload is also affected by admissions, discharges and transfers (“churn”), which can be very time-consuming but are often not reflected in midnight bed counts; by patients needing one-to-one supervision, such as those with delirium or at high risk of falling; by end-of-life care; and by ward layout. Accurate, regular acuity assessments, ideally integrated with electronic records, give managers data to make staffing decisions and to argue for resources.

What to do when staffing is unsafe

Nurses have professional responsibilities to raise concerns about unsafe staffing. Practical steps include:

1. Escalate immediately to the nurse in charge, bleep holder, site manager or equivalent, explaining the specific risks to patients.
2. Use structured communication, such as SBAR, describing the number and acuity of patients, the staff available and the risks.
3. Prioritise care based on clinical need, and communicate priorities clearly within the team.
4. Ask for help from other areas, outreach teams or senior staff.
5. Document the staffing levels, the concerns raised, who you informed, and actions taken.
6. Complete an incident report for unsafe staffing and any resulting harm or missed care.
7. Follow up through your manager, staffing committee, union or professional body if problems persist.

Nurses are rarely in a position to refuse to work, and abandoning patients is never acceptable. However, nurses can decline to take on assignments beyond their competence, and professional codes support nurses who raise concerns in good faith. Know your organisation’s escalation policy and your rights under employment law.

The role of unions and professional organisations

Nursing unions and professional associations have been central to winning safe staffing laws and policies worldwide, through research, campaigning, collective bargaining, political lobbying and, in some cases, industrial action. They also support individual nurses raising concerns. Joining and participating in these organisations amplifies nurses’ collective voice.

Staffing beyond hospitals

Most staffing research and legislation has focused on acute hospitals, but staffing matters equally in:

• Long-term care and nursing homes: where low registered nurse staffing is linked to poorer outcomes, more hospital transfers and, during the COVID-19 pandemic, higher death rates. Several countries have introduced minimum staffing standards for care homes.
• Community and home nursing: where caseloads can be very high and difficult to measure.
• Mental health services: where staffing affects safety, use of restraint and therapeutic engagement.
• Maternity services: where midwife and nurse staffing is closely linked to the safety of mothers and babies.
• Primary care: where nurse staffing affects access to preventive care and chronic disease management.

Understanding the research: how staffing studies work

Much of the evidence on nurse staffing comes from large observational studies that link data on hospital staffing, usually from nurse surveys or administrative records, with patient outcomes from hospital discharge data. Researchers adjust for differences in patients’ age, illness severity and other factors, and for hospital characteristics such as size and teaching status. Because these studies are observational, they show associations rather than proving cause and effect. However, the consistency of findings across many countries, settings and time periods, the presence of a “dose-response” relationship (more patients per nurse, worse outcomes), and natural experiments such as the introduction of ratio laws have made the evidence strong enough that most health researchers accept that nurse staffing levels genuinely affect patient safety.

More recent studies have used shift-level data, linking the staffing on each individual shift to what happened to patients during that shift. These studies, conducted in several countries, have found that patients exposed to more shifts with below-target registered nurse staffing had a higher risk of death, and that adding more nursing assistants did not compensate for missing registered nurses. Such detailed data strengthen the case that staffing on each shift matters, not just averages over a year.

Night shifts and weekends

Staffing is often lowest at night and at weekends, even though patients do not become less sick when the sun goes down. Night nurses may care for many more patients, with fewer senior staff, support services and medical colleagues available. Delirium, falls and deterioration frequently occur at night. Some studies have found higher mortality for patients admitted at weekends, and staffing has been suggested as one contributing factor. Several ratio laws set separate night-time ratios, which are usually higher than daytime ratios but still provide a protective minimum. Nurses and managers should pay particular attention to night and weekend staffing when planning rotas and escalating concerns.

Breaks, overtime and long shifts

Safe staffing also means nurses can take their breaks. When ratios are calculated without allowing for breaks, the remaining nurses must cover additional patients for long periods, effectively making staffing unsafe for part of every shift. California’s ratio law, for example, requires ratios to be maintained at all times, including during breaks, which means additional “break relief” nurses are needed. Long shifts, especially those of 12 hours or more, and excessive overtime have been associated with higher burnout, more errors and lower quality of care in some studies. Fatigue management, limits on consecutive shifts and protected rest are part of safe staffing.

Temporary staffing

When permanent staff are not available, hospitals often use bank (internal pool) or agency nurses. Temporary staff are vital for filling gaps, but heavy reliance on them is costly and may affect continuity, team working and familiarity with local systems. Good induction, orientation to the ward, buddying with permanent staff and clear handover help temporary nurses work safely. Long-term reliance on agency staff usually signals deeper problems with recruitment and retention that need structural solutions.

Floating and redeployment

Nurses are sometimes moved from their usual ward to cover shortages elsewhere (“floating” or redeployment). This can help balance staffing across a hospital, but it can also leave nurses working in unfamiliar areas with different patient groups, equipment and procedures, increasing stress and risk. Safe practice includes moving nurses to areas where their skills are transferable, providing orientation, not leaving the original ward unsafe, and listening to nurses who raise concerns about competence in the new area.

Staffing in specific settings

Emergency departments

Emergency departments face unpredictable, fluctuating demand, overcrowding and “boarding” of admitted patients waiting for ward beds. Staffing models need to account for triage, resuscitation areas, the number of patients waiting, and patients being held in corridors. Ireland, for example, developed a specific staffing framework for emergency departments. Nurses caring for admitted patients in emergency departments should be included in staffing calculations, as these patients need full inpatient-level care.

Intensive care

Intensive care units usually aim for one registered nurse to one ventilated or highly unstable patient, and one nurse to two less unstable patients, with additional senior nurses to coordinate and support. During the COVID-19 pandemic, many units were forced to stretch ratios, with nurses from other areas supporting specialist critical care nurses, a model that was associated with significant strain.

Paediatrics and neonatal care

Children need more nursing time because of developmental needs, weight-based medicines, family involvement and their inability to communicate deterioration clearly. Neonatal units have specific staffing standards based on the level of care, with intensive care babies often requiring one nurse per baby.

Maternity

Midwifery and maternity nursing staffing is linked to the safety of mothers and babies. Standards such as one-to-one care for women in established labour are widely recommended. Inquiries into failings in maternity services in several countries have identified chronic understaffing as a contributing factor.

Mental health

In inpatient mental health settings, staffing affects the ability to provide therapeutic engagement, prevent violence and self-harm, and reduce the use of restraint and seclusion. Patients requiring enhanced observation, sometimes one-to-one or more, add significant demand that must be planned for.

Long-term care

Care homes and nursing homes often have very low registered nurse staffing relative to the complexity of residents’ needs. Research has linked higher registered nurse staffing in nursing homes with fewer pressure injuries, fewer hospital transfers and better quality. Some countries have introduced minimum staffing standards, such as minimum hours of care per resident per day and requirements for a registered nurse to be on site at all times.

Workforce planning: from shifts to systems

Safe staffing on each shift depends on decisions made months and years earlier: how many nurses are trained, how many posts are funded, how well nurses are retained, and how rotas are designed. Effective workforce planning involves:

• Setting each ward’s establishment (the number of funded posts) based on systematic assessment of patient needs, not just historical budgets.
• Including “headroom” for annual leave, sickness, training and parental leave, typically adding a significant percentage on top of the core staffing need.
• Reviewing establishments regularly, at least annually, as patient needs change.
• Monitoring actual staffing against planned staffing, shift by shift.
• Linking staffing data with quality indicators, such as falls, pressure injuries and complaints.
• Reporting staffing publicly or to boards, to create accountability.

When establishments are set too low, even fully filled rotas will be unsafe. When establishments are adequate but posts remain vacant, recruitment and retention are the priority.

Technology and staffing

Electronic rostering systems, real-time acuity tools and dashboards help managers see staffing gaps quickly and move staff where they are most needed. Predictive analytics and artificial intelligence are being used to forecast demand. These tools can improve decision-making but cannot create nurses who do not exist, and they should support, not replace, professional judgement. See our guide to AI in nursing.

Making the case for safe staffing

Nurses and nurse leaders often need to persuade managers, boards, funders or politicians to invest in staffing. A strong case combines several types of evidence:

• Research evidence: the international studies linking staffing to mortality, harm and costs.
• Local data: acuity scores, planned versus actual staffing, overtime and agency spending, incidents, falls, pressure injuries, complaints and sickness absence.
• Financial analysis: the costs of agency staff, turnover (recruiting and training a replacement nurse is expensive), complications and longer stays, compared with the cost of additional permanent nurses.
• Patient and staff stories: concrete examples of missed care and its consequences, shared with consent and without identifying individuals.
• Comparisons: staffing in similar units or jurisdictions with better outcomes.

Framing safe staffing as an investment in safety, quality and efficiency, rather than simply a cost, is often more persuasive with decision-makers.

Lessons from implementing ratio laws

Jurisdictions that have introduced ratios or staffing laws offer practical lessons:

• Funding must follow: laws without funding to employ extra nurses lead to bed closures or non-compliance.
• Phased introduction allows time to recruit and train nurses.
• Monitoring and enforcement are essential; ratios that are not checked are often not met.
• Frontline nurse involvement in designing and monitoring staffing improves credibility and compliance.
• Transparent reporting builds public trust and accountability.
• Combining ratios with acuity tools helps address concerns about inflexibility.
• Evaluation provides evidence to sustain political support, as the Queensland evaluation did.

Staffing and nurse wellbeing

Unsafe staffing does not only harm patients. Nurses working in chronically understaffed environments report exhaustion, frustration, guilt about care left undone, and fear of making mistakes or being blamed. Over time this contributes to burnout, moral injury, physical injuries from rushing and lifting without help, and ultimately to nurses leaving. Improving staffing is therefore one of the most effective wellbeing interventions available, far more powerful than resilience workshops alone. See our guides to nurse burnout and moral injury.

Talking to patients and families about staffing

Patients and families often notice when wards are short-staffed, through longer waits for call bells, delayed medicines or rushed conversations. Nurses can be honest without alarming people, for example by acknowledging delays, explaining priorities, and making sure urgent needs are met. Families should be encouraged to raise concerns with the nurse in charge or through formal feedback channels, which adds valuable evidence to staffing reports. Public awareness of the link between staffing and safety has been an important driver of staffing laws.

Key messages

• Strong international evidence links lower nurse staffing with more patient deaths, harm and missed care.
• Registered nurses cannot safely be replaced by less qualified staff.
• Approaches include mandated ratios, nurse hours per patient day, acuity tools, professional judgement and legal duties.
• Ratio laws in places such as California and Queensland have been associated with better outcomes and offsetting savings.
• Safe staffing includes breaks, nights, weekends, skill mix and experience, not just numbers.
• Nurses should escalate, document and report unsafe staffing every time.

A short history of the safe staffing movement

Concerns about nurse staffing are as old as modern nursing. But the safe staffing movement gained momentum in the 1990s and 2000s, when hospital restructuring and cost-cutting in several countries reduced registered nurse numbers and replaced them with less qualified staff. Nurses reported heavier workloads and worsening care, and researchers began to measure the effects systematically. The publication of large studies linking staffing with mortality in the early 2000s provided powerful evidence. Nursing unions in California campaigned for over a decade to win the first comprehensive ratio law, and Victorian nurses won ratios through industrial action around the same time. Later, inquiries into serious failures of care in hospitals and care homes in several countries highlighted understaffing as a key factor, adding public pressure. Today, safe staffing is a central demand of nursing organisations worldwide, and an increasing number of governments are legislating or developing national frameworks.

A checklist for nurses on unsafe shifts

• Have I told the nurse in charge, specifically, why staffing is unsafe for these patients?
• Have the most acutely ill patients been identified and prioritised?
• Has help been requested from other areas or senior staff?
• Are essential safety tasks, such as observations for deteriorating patients and time-critical medicines, protected?
• Are confused or high falls-risk patients being supervised as safely as possible?
• Have I recorded the staffing levels and my concerns?
• Have I submitted an incident report after the shift?
• Have I taken a moment to check on myself and my colleagues?

Staffing and equity

Understaffing does not affect all patients equally. Hospitals serving poorer communities, rural hospitals, public facilities in low-income countries and long-term care homes often have the lowest staffing, meaning the people with the greatest health needs may receive the least nursing care. Patients who cannot easily speak up, such as people with dementia, learning disabilities, language barriers or severe illness, are particularly vulnerable when nurses are stretched, because their needs are more easily overlooked. Safe staffing is therefore a question of health equity as well as safety. Policies that set minimum standards across all facilities, combined with funding that reflects patient needs, help prevent a two-tier system in which some patients receive safe care and others do not.

Glossary of staffing terms

• Ratio: the number of patients assigned to one nurse at a given time.
• Establishment: the number of funded nursing posts for a ward or service.
• Acuity: how unwell patients are and how much nursing care they need.
• Skill mix: the balance between registered nurses and other staff.
• Headroom: extra staffing built into establishments to cover leave, sickness and training.
• Missed care: necessary care left undone because of time or staffing constraints.

Why every nurse’s voice counts

Staffing decisions can feel far removed from the bedside, made in finance meetings and government offices. Yet the evidence that changed laws in California, Australia, Wales, Scotland and elsewhere came from nurses: from surveys they completed, incidents they reported, concerns they raised and campaigns they joined. Every documented unsafe shift adds to the picture that decision-makers cannot ignore. Safe staffing is not a favour to nurses. It is a condition for safe care, and patients everywhere deserve it.

Questions to ask a prospective employer about staffing

• What is the usual nurse-to-patient ratio on day and night shifts?
• How is staffing calculated and reviewed?
• What happens when a shift is short-staffed?
• Are breaks covered by additional staff?
• How often are nurses moved to other wards?
• What support is there for new staff?

The answers will tell you a great deal about how an organisation values its nurses and its patients, and whether it is a place where you can practise safely.

Frequently asked questions

What is a safe nurse-to-patient ratio?

It depends on the setting and patients’ needs. Evidence suggests that on general wards, outcomes worsen as patients per nurse rise above around four to six during the day, and many ratio laws set minimums in this range. Intensive care typically requires one nurse for one or two patients.

Do nurse-to-patient ratios save money?

Evaluations, such as in Queensland, suggest that savings from fewer readmissions and shorter stays can offset much of the cost of additional nurses, though upfront investment is required.

Can a nurse refuse an unsafe assignment?

Rules vary. Nurses should escalate concerns, document them and seek support, and may decline tasks beyond their competence, but must not abandon patients.

Are nursing assistants counted in ratios?

Most ratio laws apply specifically to registered nurses. Nursing assistants support care but do not replace registered nurses’ responsibilities.

Why don’t all countries have ratio laws?

Reasons include cost, nurse supply, political priorities, opposition from hospital employers, and preference for other approaches.

But what if there simply are not enough nurses to meet ratios?

This is a real challenge, especially in countries with severe shortages. But experience shows that improving working conditions, including staffing, helps attract and retain nurses, and that ratio laws have sometimes drawn nurses back to the profession. Ratios can be phased in alongside investment in education and recruitment. In the meantime, transparent reporting of actual staffing, acuity-based planning, safe escalation processes and honest public conversation about the consequences of understaffing are essential. Accepting unsafe staffing as normal only deepens the shortage.

Related: Nurse staffing and nurse-to-patient ratios · The global nursing shortage explained

Sources: Aiken et al. (JAMA 2002; The Lancet 2014, RN4CAST), McHugh et al. (The Lancet 2021, Queensland ratio evaluation), Griffiths et al. research on missed care and skill mix, Nurse Staffing Levels (Wales) Act 2016, Health and Care (Staffing) (Scotland) Act 2019, Ireland Framework for Safe Nurse Staffing and Skill Mix, California Department of Public Health nurse-to-patient ratio regulations, International Council of Nurses, World Health Organization (State of the World’s Nursing).