Adoption and Variability of Longitudinal Clinical Experiences,Including Longitudinal Integrated Clerkships,in U.S. Allopathic Medical Schools: A Comprehensive Review

Introduction

Longitudinal clinical experiences (LCEs) represent a broad curricular approach in medical education that emphasizes sustained clinical engagement, continuity of care, and relationship-building with patients and healthcare teams over time. LCEs have been an evolving product of the medical education system since its development over the past 100 years as an alternative to traditional block-based education. ¹ Rather than organizing clinical learning exclusively through short, discipline-specific blocks, LCEs allow students to participate in patient care across extended periods and in a variety of clinical settings. These experiences may include longitudinal outpatient clinics, patient-following models, specialty-specific tracks, continuity-based preclinical experiences, or more comprehensive longitudinal integrated clerkships (LICs). Longitudinal clinical experiences have been associated with improved continuity of care exposure, enhanced clinical confidence, and stronger professional identity formation among medical trainees.^2,3 Among these experiences, the LIC curriculum represents a widely adopted structure that focuses on integrating multiple specialties of medical care over a more continuous timeline.

The traditional medical school curriculum adopted by most medical schools today has its roots dating back to the early 20th century. ⁴ As medicine evolved into various specialties each with its own board certification, the block rotation curriculum was born. The concept focused on building upon two years of preclinical textbook coursework by spending 4–8 weeks in each specialty for a year as a third-year medical student. This model provides structured exposure to core disciplines and remains widely used. However, critics have noted that short, specialty-specific blocks may limit continuity with patients, supervisors, and clinical teams. ⁵ In response, many medical schools have incorporated longitudinal models to better integrate clinical learning across time, specialties, and care settings.

Within the broader LCE framework, longitudinal integrated clerkships represent one of the most established and clearly defined models. LICs typically involve students participating in multiple specialties simultaneously over several months, often with repeated engagement with the same patients, preceptors, and clinical environments.^6-10 These programs may be mandatory or elective and have been implemented across rural, community, and urban settings, demonstrating adaptability to different institutional and healthcare contexts. By emphasizing sustained engagement, LICs seek to promote continuity-based clinical competencies, integrated clinical reasoning, and patient-centered care. ¹¹

Although LICs are an important example of longitudinal clinical education, many schools implement LCEs that do not meet the full structure of an LIC. These may include weekly outpatient continuity clinics during preclinical coursework, longitudinal patient panels, early clinical immersion experiences, or longitudinal tracks layered onto traditional block rotations. Some curriculum models introduce students to direct patient care early in medical school, reflecting a broader shift toward earlier and more continuous clinical exposure. ¹² This transition has also occurred alongside other curricular reforms, including problem-based learning and integrated approaches to clinical education.^13,14 As a result, LCEs may vary substantially in timing, duration, specialty integration, required participation, and curricular structure.

Longitudinal models may offer several educational benefits, including stronger relationships with clinical supervisors, improved interprofessional learning, and greater opportunities for patient advocacy. Interprofessional cooperation has been linked to improved patient outcomes, and longitudinal clinical models may help students develop more meaningful relationships with members of the healthcare team.^15-18 These experiences allow students to follow patients across encounters, clarify complex medical information, and participate more actively in care coordination. ¹⁹ However, LCE implementation can also present logistical challenges, including scheduling across clinical sites, coordinating longitudinal supervision, and balancing continuity experiences with existing curricular requirements. ²⁰

Given the growing use and variability of longitudinal models in undergraduate medical education, this study aimed to explore the current landscape of LCE implementation across medical schools in the United States. Specifically, we sought to characterize the extent of LCE adoption, describe common curricular structures, and identify national trends in longitudinal clinical programming. In this analysis, LCEs were examined broadly, with LICs considered one subset within the larger category of longitudinal educational models.

Methods

Results

The analysis of allopathic medical schools in the United States revealed that out of 158 institutions, there were 101 (64%) institutions offering a longitudinal clinical experience or longitudinal integrated clerkship as part of their curriculum, with 42 institutions offering more than one longitudinal experience. In contrast, 57 (36%) do not currently offer an LIC/LCE program. The programs that did not offer any LIC/LCE curriculum adopted the traditional curriculum: two years preclinical classwork and two years of clinical rotations. Of these 101 longitudinal clinical experiences that programs have incorporated, approximately 80% were identified as mandatory for medical students at that institution. However, 20% were deemed an elective option (Table 1).

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Table 1.

Program Qualities

Program quality	Count	Percentage
Requirement
Mandatory	81	80%
Elective	20	20%
Timeframe
Preclinical	37	37%
Clinical	22	22%
Both	42	42%
Program Type
Clinic Assignment	39	33%
Patient Assignment	7	6%
Both	33	28%
LIC	39	33%

A little over one-third (37%) of programs implemented a longitudinal clinical experience in the preclinical years (typically the first and second years of medical school). Approximately 22% had LIC/LCE options in clinical years (typically the third and fourth years of medical school). While 42% had structured longitudinal opportunities throughout both the preclinical and clinical years (Table 1). A traditional LIC model refers to continuous clinical experiences where students work with different specialties throughout each week. Alternative LCE model refers to those with an elective LCE curriculum or clinical assignments in their first/second years of medical school. For example, a few programs offer specific tracks, often in primary care, that incorporate longitudinal patient care experiences. When exploring the type of program available at each institution, one-third had a clinic assignment option. This was typically structured as one session every other week with a local primary care clinic. Only 6% of programs had students assigned to a specific patient as the extent of their longitudinal patient care experience. Thirty-three (28%) had both a clinic and a patient assignment. Finally, 39 (33%) programs evaluated had incorporated the traditional Longitudinal Integrated Clerkship curriculum (Table 1).

With regards to length of these programs, the average length was 24months, and the median length was 18 months. The program lengths ranged from 2 to 48 months long (Figure 1). Six of the programs ranged were 6 months or less (6, 6%). Thirty institutions had a program that ranged from 6 months to 1 year (30%). Fourteen ranged from 12 to 18 months (14%). Fourteen ranged from 18 to 24 months (14%). One ranged from 24 to 30 months (1, 1%). Eleven ranged from 30 to 36 months (11%). Twenty-four ranged from 42 to 48 months (24%).OPEN IN VIEWER

Discussion

The findings of this study reveal that longitudinal clinical experiences are increasingly being adopted across allopathic medical schools in the United States, with 101 institutions offering some form of LIC or LCE. A previous review identified 69 allopathic medical schools offering longitudinal clinical programs as of August 2014, whereas the present study identified 101 schools offering longitudinal clinical experiences, representing a notable increase in institutional adoption over time. ²¹ It is important to note that since August of 2014 to November 2024, there was an increase from 137 to 158 U.S. allopathic medical schools. However, there was still a 14% increase in the proportion of medical schools utilizing a longitudinal clinical curriculum over this time period (50% vs 64%). Although the number of longitudinal programs increased compared to prior reports, it remains unclear whether this growth is driven primarily by expansion of traditional LICs or by broader adoption of alternative longitudinal clinical models. There has been a substantial increase in the number of allopathic medical schools implementing some form of longitudinal clinical experience for medical students in the past seven years.

These programs vary significantly in structure, with some schools integrating longitudinal clinical experiences into the first two years of medical education, others in the final two years, and some spanning the entire four years. Additionally, some are mandatory, while others are offered as an elective. The models of longitudinal clinical programs range from emphasizing patient or clinic attachments, to the traditional LIC structure. This diversity reflects the adaptability of the longitudinal model to different institutional goals.

The variability in longitudinal curriculum implementation identified in this study highlights the flexibility of the model to meet the needs of different institutions and student populations. For example, programs that integrate LCEs into the first two years of medical school may provide students with early exposure to clinical practice and thus reinforce basic science learning through connecting theory to practice. Conversely, programs that focus on the final two years may allow students to consolidate their clinical skills and prepare for board exams and residency in a more immersive and realistic environment. ⁹

Despite its many benefits, the LIC model is not without challenges. Implementing LICs and LCEs requires significant institutional commitment, including the allocation of resources for faculty development, curriculum design, and administrative support. ²² Additionally, the success of LICs/LCEs depends on the availability of clinical sites and preceptors who are willing to engage in longitudinal teaching relationships. ²³ These challenges may explain why some institutions offer these longitudinal experiences as elective rather than mandatory programs.

Limitations

The reliance on publicly available information and self-reported data from institutions could introduce inaccuracies, particularly for programs that are newly established or undergoing changes. This approach is also vulnerable to information bias from incomplete, outdated, or inconsistently reported website content, as well as publication/visibility bias in which schools with well-established or highly promoted longitudinal curricula may be more likely to feature programs prominently online. Because program details were derived from web-based sources, some LIC/LCEs may have been misclassified or missed entirely if descriptions were limited, archived, or not publicly accessible. In addition, the absence of primary-source validation (direct confirmation with curriculum deans or LIC program directors) limits our ability to verify program status (active/inactive), structure, and whether experiences are mandatory versus elective. Although direct institutional outreach might have clarified select discrepancies, we did not pursue program-by-program confirmation because response rates and the level of detail provided would likely vary across schools, introducing differential ascertainment and reducing the standardization and reproducibility of the data collection process. As a result, classifications were based uniformly on publicly available sources, which may not fully capture internal curricular details or recent programmatic changes. Additionally, the study does not explore the quality or outcomes of these specific LIC/LCE programs, such as student satisfaction, clinical performance, or long-term career impacts, which limits the ability to draw conclusions about the effectiveness of different longitudinal models. The study focuses exclusively on allopathic medical schools, excluding osteopathic and international institutions, which may limit the generalizability of the findings. In particular, the exclusion of osteopathic (DO-granting) schools likely yields an incomplete picture of longitudinal clinical training nationally and may underestimate the prevalence and diversity of longitudinal models in the U.S. These limitations highlight the need for further research, including qualitative studies and longitudinal assessments, to provide a more comprehensive understanding of LIC programs in the U.S.

Conclusion

The growing adoption of longitudinal clinical curricula in allopathic medical schools in the United States reflects the recognition of its potential to enhance medical education. The variability in implementation observed in this study underscores the adaptability of the LIC model to different institutional contexts and educational goals. By providing students with opportunities for continuity of care, authentic clinical experiences, and strong mentoring relationships, LICs and LCEs can play a critical role in preparing future physicians to meet the complex demands of modern healthcare. Future research should explore the long-term outcomes of LIC graduates, including their performance in residency and their ability to provide patient-centered, value-basedcare.